From 72fe8b927bfdab9bd90c4ccb05a6c739e6c40d5f Mon Sep 17 00:00:00 2001
From: ella <ella@automattic.com>
Date: Mon, 19 Oct 2026 15:17:26 -0700
Subject: [PATCH 1/6] Say when an autosave got no response from the server

When the request fails before any response arrives, the notice now says
"Auto-save failed because there was no response from the server." instead
of only "Auto-save failed."

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../editor/src/store/utils/notice-builder.js  |  9 ++++++-
 .../src/store/utils/test/notice-builder.js    | 10 ++++++++
 .../various/autosave-failure-notice.spec.js   | 24 ++++++++++---------
 3 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/packages/editor/src/store/utils/notice-builder.js b/packages/editor/src/store/utils/notice-builder.js
index 0713cdee670900..8c15714a22bf8a 100644
--- a/packages/editor/src/store/utils/notice-builder.js
+++ b/packages/editor/src/store/utils/notice-builder.js
@@ -5,6 +5,10 @@ const AUTO_SAVE_FAILURE_NOTICE = __(
 	'Auto-save failed. You can also save manually.'
 );
 
+const AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE = __(
+	'Auto-save failed because there was no response from the server. You can also save manually.'
+);
+
 const AUTO_SAVE_OFFLINE_FAILURE_NOTICE = __(
 	'Auto-save failed because you were offline. You can also save manually once you’re back online.'
 );
@@ -150,7 +154,10 @@ export function getNotificationArgumentsForSaveFail( data ) {
 			: messages.default;
 
 	if ( options?.isAutosave ) {
-		noticeMessage = AUTO_SAVE_FAILURE_NOTICE;
+		noticeMessage =
+			error.code === 'fetch_error'
+				? AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE
+				: AUTO_SAVE_FAILURE_NOTICE;
 	}
 
 	return [ noticeMessage, { id } ];
diff --git a/packages/editor/src/store/utils/test/notice-builder.js b/packages/editor/src/store/utils/test/notice-builder.js
index 58036303e017d3..244baa47b3b94b 100644
--- a/packages/editor/src/store/utils/test/notice-builder.js
+++ b/packages/editor/src/store/utils/test/notice-builder.js
@@ -158,6 +158,16 @@ describe( 'getNotificationArgumentsForSaveFail()', () => {
 			],
 			{ isAutosave: true },
 		],
+		[
+			'when the autosave got no response',
+			'fetch_error',
+			[ 'publish', 'publish' ],
+			[
+				'Auto-save failed because there was no response from the server. You can also save manually.',
+				{ id: 'editor-autosave' },
+			],
+			{ isAutosave: true },
+		],
 	].forEach(
 		( [
 			description,
diff --git a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
index 0a44bb78bdeecf..879da034d680e9 100644
--- a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
+++ b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
@@ -5,6 +5,9 @@ const {
 
 const AUTOSAVE_FAILED = 'Auto-save failed. You can also save manually.';
 
+const AUTOSAVE_FAILED_NO_RESPONSE =
+	'Auto-save failed because there was no response from the server. You can also save manually.';
+
 const UPDATING_FAILED_OFFLINE =
 	'Updating failed because you were offline. Please verify your connection and try again.';
 
@@ -96,11 +99,11 @@ test.describe( 'Autosave failure notice', () => {
 			'link-in-message',
 			withDetails( 'Blocked. Learn more (https://example.com).' ),
 		],
-		// TODO: Say the server could not be reached, and retry right away.
+		// TODO: Retry right away.
 		[
 			'connection dropped before a response',
 			'dropped-connection',
-			AUTOSAVE_FAILED,
+			AUTOSAVE_FAILED_NO_RESPONSE,
 		],
 		// TODO: Show the status code.
 		[ 'error without a message', 'no-message', AUTOSAVE_FAILED ],
@@ -143,11 +146,10 @@ test.describe( 'Autosave failure notice', () => {
 			'redirect-to-login',
 			withDetails( 'The response is not a valid JSON response.' ),
 		],
-		// TODO: Say the server could not be reached.
 		[
 			'redirected to another site',
 			'redirect-to-other-site',
-			AUTOSAVE_FAILED,
+			AUTOSAVE_FAILED_NO_RESPONSE,
 		],
 		[
 			'maintenance mode',
@@ -298,11 +300,11 @@ test.describe( 'Autosave failure notice', () => {
 				.locator( '.notices-inline-notices__notice' );
 			await expect( notice ).toContainText(
 				new RegExp(
-					`${ AUTOSAVE_FAILED.replaceAll( '.', '\\.' ) } Retrying in (10|9) seconds\\.`
+					`${ AUTOSAVE_FAILED_NO_RESPONSE.replaceAll( '.', '\\.' ) } Retrying in (10|9) seconds\\.`
 				)
 			);
 			await expect( notice ).toContainText(
-				`${ AUTOSAVE_FAILED } Retrying in 7 seconds.`
+				`${ AUTOSAVE_FAILED_NO_RESPONSE } Retrying in 7 seconds.`
 			);
 		} );
 
@@ -323,7 +325,7 @@ test.describe( 'Autosave failure notice', () => {
 				.getByRole( 'region', { name: 'Editor content' } )
 				.locator( '.notices-inline-notices__notice' );
 			await expect( notice ).toContainText(
-				`${ AUTOSAVE_FAILED } Retrying…`
+				`${ AUTOSAVE_FAILED_NO_RESPONSE } Retrying…`
 			);
 			await expect( notice ).toHaveCount( 0 );
 		} );
@@ -355,7 +357,7 @@ test.describe( 'Autosave failure notice', () => {
 					}
 				}
 				expect( await autosaveFailure.getNotices() ).toEqual( [
-					AUTOSAVE_FAILED,
+					AUTOSAVE_FAILED_NO_RESPONSE,
 				] );
 			} );
 		}
@@ -366,7 +368,7 @@ test.describe( 'Autosave failure notice', () => {
 			await autosaveFailure.fail( 'dropped-connection' );
 			await autosaveFailure.autosave();
 			expect( await autosaveFailure.getNotices() ).toEqual( [
-				AUTOSAVE_FAILED,
+				AUTOSAVE_FAILED_NO_RESPONSE,
 			] );
 
 			await autosaveFailure.stopFailing();
@@ -381,7 +383,7 @@ test.describe( 'Autosave failure notice', () => {
 			await autosaveFailure.fail( 'dropped-connection' );
 			await autosaveFailure.autosave();
 			expect( await autosaveFailure.getNotices() ).toEqual( [
-				AUTOSAVE_FAILED,
+				AUTOSAVE_FAILED_NO_RESPONSE,
 			] );
 
 			await autosaveFailure.stopFailing();
@@ -400,7 +402,7 @@ test.describe( 'Autosave failure notice', () => {
 			await autosaveFailure.fail( 'dropped-connection' );
 			await autosaveFailure.autosave();
 			expect( await autosaveFailure.getNotices() ).toEqual( [
-				AUTOSAVE_FAILED,
+				AUTOSAVE_FAILED_NO_RESPONSE,
 			] );
 
 			await context.setOffline( true );

From 583a8a4a714e6208d56e91d6f48fd668fce3007e Mon Sep 17 00:00:00 2001
From: ella <ella@automattic.com>
Date: Mon, 19 Oct 2026 17:45:04 -0700
Subject: [PATCH 2/6] Show the HTTP status in save failure details

apiFetch now keeps the response's status in the error's `data` when the
body doesn't include one, and the address a redirected request ended at
for `invalid_json` errors. The save failure details show "Error 502" and
so on instead of "The response is not a valid JSON response.", and an
autosave redirected to the login page says you may have been logged out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 packages/api-fetch/CHANGELOG.md               |  4 ++
 .../api-fetch/src/test/index.jsdom.test.js    | 61 +++++++++++++++++++
 packages/api-fetch/src/utils/response.ts      | 43 ++++++++++++-
 packages/editor/src/store/actions.js          | 20 ++++--
 .../src/store/test/actions.jsdom.test.js      | 22 ++++++-
 .../editor/src/store/utils/notice-builder.js  | 31 ++++++++--
 .../src/store/utils/test/notice-builder.js    | 16 +++++
 .../various/autosave-failure-notice.spec.js   | 43 +++++++------
 8 files changed, 209 insertions(+), 31 deletions(-)

diff --git a/packages/api-fetch/CHANGELOG.md b/packages/api-fetch/CHANGELOG.md
index 5fb351605b48ac..2e60545b9d5df3 100644
--- a/packages/api-fetch/CHANGELOG.md
+++ b/packages/api-fetch/CHANGELOG.md
@@ -6,6 +6,10 @@
 
 -   Raise the minimum required Node.js version to `>=22.13.0`, for stable `require(esm)` support ([#84313](https://github.com/WordPress/gutenberg/pull/84313)).
 
+### Enhancements
+
+-   Add the response's status to the `data` of a thrown error when the error body doesn't include one, including `invalid_json` errors, which also include the address a redirected request ended at as `data.url` ([#85157](https://github.com/WordPress/gutenberg/pull/85157)).
+
 ## 7.57.0 (2026-10-07)
 
 ## 7.56.0 (2026-09-23)
diff --git a/packages/api-fetch/src/test/index.jsdom.test.js b/packages/api-fetch/src/test/index.jsdom.test.js
index f848e55c43c88e..fa48ac9b2f12d6 100644
--- a/packages/api-fetch/src/test/index.jsdom.test.js
+++ b/packages/api-fetch/src/test/index.jsdom.test.js
@@ -131,6 +131,47 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'bad_request',
 			message: 'Bad Request',
+			data: { status: 400 },
+		} );
+	} );
+
+	it( 'should add the status to the data of an error response', async () => {
+		globalThis.fetch.mockResolvedValue( {
+			ok: false,
+			status: 500,
+			async json() {
+				return {
+					code: 'db_update_error',
+					message: 'Could not update post in the database.',
+					data: { reason: 'test' },
+				};
+			},
+		} );
+
+		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
+			code: 'db_update_error',
+			message: 'Could not update post in the database.',
+			data: { reason: 'test', status: 500 },
+		} );
+	} );
+
+	it( 'should keep the data of an error response', async () => {
+		globalThis.fetch.mockResolvedValue( {
+			ok: false,
+			status: 403,
+			async json() {
+				return {
+					code: 'rest_forbidden',
+					message: 'Forbidden',
+					data: { status: 401 },
+				};
+			},
+		} );
+
+		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
+			code: 'rest_forbidden',
+			message: 'Forbidden',
+			data: { status: 401 },
 		} );
 	} );
 
@@ -146,6 +187,7 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'invalid_json',
 			message: 'The response is not a valid JSON response.',
+			data: { status: 200 },
 		} );
 	} );
 
@@ -161,6 +203,7 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'invalid_json',
 			message: 'The response is not a valid JSON response.',
+			data: { status: 200 },
 		} );
 	} );
 
@@ -234,6 +277,22 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'invalid_json',
 			message: 'The response is not a valid JSON response.',
+			data: { status: 200 },
+		} );
+	} );
+
+	it( 'should return the redirect address with an invalid JSON error', async () => {
+		const response = new Response( '<html></html>', { status: 200 } );
+		Object.defineProperties( response, {
+			redirected: { value: true },
+			url: { value: 'http://example.com/wp-login.php' },
+		} );
+		globalThis.fetch.mockResolvedValue( response );
+
+		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
+			code: 'invalid_json',
+			message: 'The response is not a valid JSON response.',
+			data: { status: 200, url: 'http://example.com/wp-login.php' },
 		} );
 	} );
 
@@ -245,6 +304,7 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'invalid_json',
 			message: 'The response is not a valid JSON response.',
+			data: { status: 500 },
 		} );
 	} );
 
@@ -357,6 +417,7 @@ describe( 'apiFetch', () => {
 
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'rest_cookie_invalid_nonce',
+			data: { status: 403 },
 		} );
 	} );
 
diff --git a/packages/api-fetch/src/utils/response.ts b/packages/api-fetch/src/utils/response.ts
index 358856718470a1..eb0b607a6fef85 100644
--- a/packages/api-fetch/src/utils/response.ts
+++ b/packages/api-fetch/src/utils/response.ts
@@ -32,10 +32,40 @@ async function parseJsonAndNormalizeError(
 		throw {
 			code: 'invalid_json',
 			message: __( 'The response is not a valid JSON response.' ),
+			...getResponseData( response ),
 		};
 	}
 }
 
+/**
+ * Returns the response's status, and the address it was redirected to, in the
+ * shape of a REST error's `data`.
+ *
+ * @param response
+ * @return Object with a `data` property, or an empty object.
+ */
+function getResponseData( response: Response ) {
+	if ( typeof response.status !== 'number' ) {
+		return {};
+	}
+	return {
+		data: {
+			status: response.status,
+			...( response.redirected && { url: response.url } ),
+		},
+	};
+}
+
+/**
+ * Returns whether a value is an object other than an array.
+ *
+ * @param value
+ * @return Whether the value is a plain object.
+ */
+function isPlainObject( value: unknown ): value is Record< string, any > {
+	return !! value && typeof value === 'object' && ! Array.isArray( value );
+}
+
 /**
  * Parses the apiFetch response properly and normalize response errors.
  *
@@ -75,5 +105,16 @@ export async function parseAndThrowError(
 	}
 
 	// Parse the response JSON and throw it as an error.
-	throw await parseJsonAndNormalizeError( response );
+	const error = await parseJsonAndNormalizeError( response );
+
+	// Like WordPress's own REST errors, an error carries the status in `data`.
+	if (
+		isPlainObject( error ) &&
+		( error.data === undefined || isPlainObject( error.data ) ) &&
+		error.data?.status === undefined &&
+		typeof response.status === 'number'
+	) {
+		throw { ...error, data: { ...error.data, status: response.status } };
+	}
+	throw error;
 }
diff --git a/packages/editor/src/store/actions.js b/packages/editor/src/store/actions.js
index d72fce8de7db81..5f94c7d6e4a4d2 100644
--- a/packages/editor/src/store/actions.js
+++ b/packages/editor/src/store/actions.js
@@ -23,7 +23,7 @@ import {
 	doActionAsync,
 } from '@wordpress/hooks';
 import { store as preferencesStore } from '@wordpress/preferences';
-import { __ } from '@wordpress/i18n';
+import { __, sprintf } from '@wordpress/i18n';
 import { localAutosaveSet } from './local-autosave';
 import {
 	getNotificationArgumentsForSaveSuccess,
@@ -39,9 +39,13 @@ import { AUTOSAVE_RETRY_SLOT } from './constants';
 const { getEntitySnapshot } = unlock( coreDataPrivateApis );
 
 // Error codes whose message is generated by the client rather than returned by
-// the server. Their messages restate what the notice already says, so there are
-// no details worth disclosing.
-const CLIENT_GENERATED_ERROR_CODES = [ 'offline_error', 'fetch_error' ];
+// the server. Their messages add nothing to the notice, so they are not shown as
+// details.
+const CLIENT_GENERATED_ERROR_CODES = [
+	'offline_error',
+	'fetch_error',
+	'invalid_json',
+];
 
 // Block-level elements whose end is a line break once markup is removed, so two
 // sentences in separate paragraphs don't run together.
@@ -408,12 +412,20 @@ export const savePost =
 				// A PHP fatal error's message, with its stack trace, comes in
 				// `data.error`, apart from the generic message WordPress shows.
 				const phpError = error.data?.error?.message;
+				const status = error.data?.status;
 				const details = [
 					error.message &&
 					! CLIENT_GENERATED_ERROR_CODES.includes( error.code )
 						? getFailureDetails( error.message )
 						: '',
 					typeof phpError === 'string' ? phpError.trim() : '',
+					Number.isInteger( status ) && status >= 400
+						? sprintf(
+								/* translators: %d: HTTP status code, such as 500. */
+								__( 'Error %d' ),
+								status
+							)
+						: '',
 				]
 					.filter( Boolean )
 					.join( '\n\n' );
diff --git a/packages/editor/src/store/test/actions.jsdom.test.js b/packages/editor/src/store/test/actions.jsdom.test.js
index 553f314953d7fa..61b924f0fc5c0d 100644
--- a/packages/editor/src/store/test/actions.jsdom.test.js
+++ b/packages/editor/src/store/test/actions.jsdom.test.js
@@ -427,7 +427,7 @@ describe( 'Post actions', () => {
 						},
 					},
 				},
-				'There has been a critical error on this website.\n\nUncaught Error: Call to undefined function f() in /var/www/html/a.php:2\nStack trace:\n#0 {main}\n  thrown',
+				'There has been a critical error on this website.\n\nUncaught Error: Call to undefined function f() in /var/www/html/a.php:2\nStack trace:\n#0 {main}\n  thrown\n\nError 500',
 			],
 			[
 				'ignores a PHP error message that is not a string',
@@ -436,7 +436,25 @@ describe( 'Post actions', () => {
 					message: 'Server error.',
 					data: { status: 500, error: { message: [ 'unexpected' ] } },
 				},
-				'Server error.',
+				'Server error.\n\nError 500',
+			],
+			[
+				'shows the status of a response that is not JSON',
+				{
+					code: 'invalid_json',
+					message: 'The response is not a valid JSON response.',
+					data: { status: 502 },
+				},
+				'Error 502',
+			],
+			[
+				'shows no details for a successful response that is not JSON',
+				{
+					code: 'invalid_json',
+					message: 'The response is not a valid JSON response.',
+					data: { status: 200 },
+				},
+				undefined,
 			],
 		] )( '%s', async ( _description, serverError, expectedDetails ) => {
 			const post = {
diff --git a/packages/editor/src/store/utils/notice-builder.js b/packages/editor/src/store/utils/notice-builder.js
index 8c15714a22bf8a..83c230c5464396 100644
--- a/packages/editor/src/store/utils/notice-builder.js
+++ b/packages/editor/src/store/utils/notice-builder.js
@@ -9,10 +9,30 @@ const AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE = __(
 	'Auto-save failed because there was no response from the server. You can also save manually.'
 );
 
+const AUTO_SAVE_LOGGED_OUT_FAILURE_NOTICE = __(
+	'Auto-save failed because you may have been logged out.'
+);
+
 const AUTO_SAVE_OFFLINE_FAILURE_NOTICE = __(
 	'Auto-save failed because you were offline. You can also save manually once you’re back online.'
 );
 
+/**
+ * Returns whether an address is the login page, where a request lands once the
+ * session has ended.
+ *
+ * @param {string} [url] Address a request was redirected to.
+ *
+ * @return {boolean} Whether the address is the login page.
+ */
+function isLoginPage( url ) {
+	try {
+		return new URL( url ).pathname.endsWith( '/wp-login.php' );
+	} catch {
+		return false;
+	}
+}
+
 /**
  * Builds the arguments for a success notification dispatch.
  *
@@ -154,10 +174,13 @@ export function getNotificationArgumentsForSaveFail( data ) {
 			: messages.default;
 
 	if ( options?.isAutosave ) {
-		noticeMessage =
-			error.code === 'fetch_error'
-				? AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE
-				: AUTO_SAVE_FAILURE_NOTICE;
+		if ( error.code === 'fetch_error' ) {
+			noticeMessage = AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE;
+		} else if ( isLoginPage( error.data?.url ) ) {
+			noticeMessage = AUTO_SAVE_LOGGED_OUT_FAILURE_NOTICE;
+		} else {
+			noticeMessage = AUTO_SAVE_FAILURE_NOTICE;
+		}
 	}
 
 	return [ noticeMessage, { id } ];
diff --git a/packages/editor/src/store/utils/test/notice-builder.js b/packages/editor/src/store/utils/test/notice-builder.js
index 244baa47b3b94b..72a2d46ddc5486 100644
--- a/packages/editor/src/store/utils/test/notice-builder.js
+++ b/packages/editor/src/store/utils/test/notice-builder.js
@@ -168,6 +168,20 @@ describe( 'getNotificationArgumentsForSaveFail()', () => {
 			],
 			{ isAutosave: true },
 		],
+		[
+			'when the autosave was redirected to the login page',
+			'invalid_json',
+			[ 'publish', 'publish' ],
+			[
+				'Auto-save failed because you may have been logged out.',
+				{ id: 'editor-autosave' },
+			],
+			{ isAutosave: true },
+			{
+				status: 200,
+				url: 'http://example.com/wp-login.php?redirect_to=x',
+			},
+		],
 	].forEach(
 		( [
 			description,
@@ -175,10 +189,12 @@ describe( 'getNotificationArgumentsForSaveFail()', () => {
 			[ postStatus, editsStatus ],
 			expectedValue,
 			options = {},
+			data,
 		] ) => {
 			it( description, () => {
 				post.status = postStatus;
 				error.code = errorCode;
+				error.data = data;
 				edits.status = editsStatus;
 				expect(
 					getNotificationArgumentsForSaveFail( {
diff --git a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
index 879da034d680e9..a9b91b0636eeb5 100644
--- a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
+++ b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
@@ -5,6 +5,9 @@ const {
 
 const AUTOSAVE_FAILED = 'Auto-save failed. You can also save manually.';
 
+const AUTOSAVE_FAILED_LOGGED_OUT =
+	'Auto-save failed because you may have been logged out.';
+
 const AUTOSAVE_FAILED_NO_RESPONSE =
 	'Auto-save failed because there was no response from the server. You can also save manually.';
 
@@ -92,12 +95,16 @@ test.describe( 'Autosave failure notice', () => {
 		[
 			'database connection lost',
 			'database-connection-lost',
-			withDetails( 'Error establishing a database connection' ),
+			withDetails(
+				'Error establishing a database connection\n\nError 500'
+			),
 		],
 		[
 			'error message containing a link',
 			'link-in-message',
-			withDetails( 'Blocked. Learn more (https://example.com).' ),
+			withDetails(
+				'Blocked. Learn more (https://example.com).\n\nError 403'
+			),
 		],
 		// TODO: Retry right away.
 		[
@@ -105,46 +112,42 @@ test.describe( 'Autosave failure notice', () => {
 			'dropped-connection',
 			AUTOSAVE_FAILED_NO_RESPONSE,
 		],
-		// TODO: Show the status code.
-		[ 'error without a message', 'no-message', AUTOSAVE_FAILED ],
+		[ 'error without a message', 'no-message', withDetails( 'Error 500' ) ],
 		[
 			'error with a plain text message',
 			'plain-message',
-			withDetails( 'Something went wrong on the server.' ),
+			withDetails( 'Something went wrong on the server.\n\nError 500' ),
 		],
 		[
 			'permission denied',
 			'permission',
-			withDetails( 'Sorry, you are not allowed to edit this post.' ),
+			withDetails(
+				'Sorry, you are not allowed to edit this post.\n\nError 403'
+			),
 		],
+		// The error's `data` is the database error, so there is no status in it.
 		[
 			'database write failed',
 			'database-write',
 			withDetails( 'Could not update post in the database.' ),
 		],
-		// TODO: Show the status code (502) instead.
-		[
-			'HTML error page',
-			'bad-gateway',
-			withDetails( 'The response is not a valid JSON response.' ),
-		],
-		// TODO: Show the status code (429) instead.
+		[ 'HTML error page', 'bad-gateway', withDetails( 'Error 502' ) ],
 		[
 			'too many requests',
 			'too-many-requests',
-			withDetails( 'The response is not a valid JSON response.' ),
+			withDetails( 'Error 429' ),
 		],
+		// The error is printed before the headers, so the status stays 200.
 		// TODO: Show the PHP error the response includes in `data.error`.
 		[
 			'PHP fatal error printed before the JSON',
 			'fatal-error-displayed',
-			withDetails( 'The response is not a valid JSON response.' ),
+			AUTOSAVE_FAILED,
 		],
-		// TODO: Say the session may have expired.
 		[
 			'redirected to the login page',
 			'redirect-to-login',
-			withDetails( 'The response is not a valid JSON response.' ),
+			AUTOSAVE_FAILED_LOGGED_OUT,
 		],
 		[
 			'redirected to another site',
@@ -155,7 +158,7 @@ test.describe( 'Autosave failure notice', () => {
 			'maintenance mode',
 			'maintenance',
 			withDetails(
-				'Briefly unavailable for scheduled maintenance. Check back in a minute.'
+				'Briefly unavailable for scheduled maintenance. Check back in a minute.\n\nError 503'
 			),
 		],
 		// TODO: Report the failure; the autosave fails without a notice.
@@ -210,7 +213,7 @@ test.describe( 'Autosave failure notice', () => {
 		await autosaveFailure.autosave();
 		// TODO: Say the session expired and offer to log in again.
 		expect( await autosaveFailure.getNotices() ).toEqual( [
-			withDetails( 'Cookie check failed' ),
+			withDetails( 'Cookie check failed\n\nError 403' ),
 		] );
 	} );
 
@@ -223,7 +226,7 @@ test.describe( 'Autosave failure notice', () => {
 		const title = await autosaveFailure.autosave();
 		// TODO: Don't report a failure; the autosave was stored.
 		expect( await autosaveFailure.getNotices() ).toEqual( [
-			withDetails( 'The response is not a valid JSON response.' ),
+			AUTOSAVE_FAILED,
 		] );
 
 		const postId = await page.evaluate( () =>

From a2a159e3abe4aea42561312945491913b2613d27 Mon Sep 17 00:00:00 2001
From: ella <ella@automattic.com>
Date: Mon, 19 Oct 2026 17:53:01 -0700
Subject: [PATCH 3/6] Keep only the status on apiFetch's invalid JSON errors

Drop the redirect address, the status added to other errors, and the
logged-out wording.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 packages/api-fetch/CHANGELOG.md               |  2 +-
 .../api-fetch/src/test/index.jsdom.test.js    | 57 -------------------
 packages/api-fetch/src/utils/response.ts      | 44 +-------------
 .../editor/src/store/utils/notice-builder.js  | 31 ++--------
 .../src/store/utils/test/notice-builder.js    | 16 ------
 .../various/autosave-failure-notice.spec.js   |  9 ++-
 6 files changed, 11 insertions(+), 148 deletions(-)

diff --git a/packages/api-fetch/CHANGELOG.md b/packages/api-fetch/CHANGELOG.md
index 2e60545b9d5df3..1e26320480faf4 100644
--- a/packages/api-fetch/CHANGELOG.md
+++ b/packages/api-fetch/CHANGELOG.md
@@ -8,7 +8,7 @@
 
 ### Enhancements
 
--   Add the response's status to the `data` of a thrown error when the error body doesn't include one, including `invalid_json` errors, which also include the address a redirected request ended at as `data.url` ([#85157](https://github.com/WordPress/gutenberg/pull/85157)).
+-   Include the response's status as `data.status` in `invalid_json` errors ([#85157](https://github.com/WordPress/gutenberg/pull/85157)).
 
 ## 7.57.0 (2026-10-07)
 
diff --git a/packages/api-fetch/src/test/index.jsdom.test.js b/packages/api-fetch/src/test/index.jsdom.test.js
index fa48ac9b2f12d6..cbbf614266a45c 100644
--- a/packages/api-fetch/src/test/index.jsdom.test.js
+++ b/packages/api-fetch/src/test/index.jsdom.test.js
@@ -131,47 +131,6 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'bad_request',
 			message: 'Bad Request',
-			data: { status: 400 },
-		} );
-	} );
-
-	it( 'should add the status to the data of an error response', async () => {
-		globalThis.fetch.mockResolvedValue( {
-			ok: false,
-			status: 500,
-			async json() {
-				return {
-					code: 'db_update_error',
-					message: 'Could not update post in the database.',
-					data: { reason: 'test' },
-				};
-			},
-		} );
-
-		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
-			code: 'db_update_error',
-			message: 'Could not update post in the database.',
-			data: { reason: 'test', status: 500 },
-		} );
-	} );
-
-	it( 'should keep the data of an error response', async () => {
-		globalThis.fetch.mockResolvedValue( {
-			ok: false,
-			status: 403,
-			async json() {
-				return {
-					code: 'rest_forbidden',
-					message: 'Forbidden',
-					data: { status: 401 },
-				};
-			},
-		} );
-
-		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
-			code: 'rest_forbidden',
-			message: 'Forbidden',
-			data: { status: 401 },
 		} );
 	} );
 
@@ -281,21 +240,6 @@ describe( 'apiFetch', () => {
 		} );
 	} );
 
-	it( 'should return the redirect address with an invalid JSON error', async () => {
-		const response = new Response( '<html></html>', { status: 200 } );
-		Object.defineProperties( response, {
-			redirected: { value: true },
-			url: { value: 'http://example.com/wp-login.php' },
-		} );
-		globalThis.fetch.mockResolvedValue( response );
-
-		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
-			code: 'invalid_json',
-			message: 'The response is not a valid JSON response.',
-			data: { status: 200, url: 'http://example.com/wp-login.php' },
-		} );
-	} );
-
 	it( 'should return invalid JSON error for an error response with an empty body', async () => {
 		globalThis.fetch.mockResolvedValue(
 			new Response( '', { status: 500 } )
@@ -417,7 +361,6 @@ describe( 'apiFetch', () => {
 
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'rest_cookie_invalid_nonce',
-			data: { status: 403 },
 		} );
 	} );
 
diff --git a/packages/api-fetch/src/utils/response.ts b/packages/api-fetch/src/utils/response.ts
index eb0b607a6fef85..ff1d6641a1ff61 100644
--- a/packages/api-fetch/src/utils/response.ts
+++ b/packages/api-fetch/src/utils/response.ts
@@ -32,40 +32,11 @@ async function parseJsonAndNormalizeError(
 		throw {
 			code: 'invalid_json',
 			message: __( 'The response is not a valid JSON response.' ),
-			...getResponseData( response ),
+			data: { status: response.status },
 		};
 	}
 }
 
-/**
- * Returns the response's status, and the address it was redirected to, in the
- * shape of a REST error's `data`.
- *
- * @param response
- * @return Object with a `data` property, or an empty object.
- */
-function getResponseData( response: Response ) {
-	if ( typeof response.status !== 'number' ) {
-		return {};
-	}
-	return {
-		data: {
-			status: response.status,
-			...( response.redirected && { url: response.url } ),
-		},
-	};
-}
-
-/**
- * Returns whether a value is an object other than an array.
- *
- * @param value
- * @return Whether the value is a plain object.
- */
-function isPlainObject( value: unknown ): value is Record< string, any > {
-	return !! value && typeof value === 'object' && ! Array.isArray( value );
-}
-
 /**
  * Parses the apiFetch response properly and normalize response errors.
  *
@@ -105,16 +76,5 @@ export async function parseAndThrowError(
 	}
 
 	// Parse the response JSON and throw it as an error.
-	const error = await parseJsonAndNormalizeError( response );
-
-	// Like WordPress's own REST errors, an error carries the status in `data`.
-	if (
-		isPlainObject( error ) &&
-		( error.data === undefined || isPlainObject( error.data ) ) &&
-		error.data?.status === undefined &&
-		typeof response.status === 'number'
-	) {
-		throw { ...error, data: { ...error.data, status: response.status } };
-	}
-	throw error;
+	throw await parseJsonAndNormalizeError( response );
 }
diff --git a/packages/editor/src/store/utils/notice-builder.js b/packages/editor/src/store/utils/notice-builder.js
index 83c230c5464396..8c15714a22bf8a 100644
--- a/packages/editor/src/store/utils/notice-builder.js
+++ b/packages/editor/src/store/utils/notice-builder.js
@@ -9,30 +9,10 @@ const AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE = __(
 	'Auto-save failed because there was no response from the server. You can also save manually.'
 );
 
-const AUTO_SAVE_LOGGED_OUT_FAILURE_NOTICE = __(
-	'Auto-save failed because you may have been logged out.'
-);
-
 const AUTO_SAVE_OFFLINE_FAILURE_NOTICE = __(
 	'Auto-save failed because you were offline. You can also save manually once you’re back online.'
 );
 
-/**
- * Returns whether an address is the login page, where a request lands once the
- * session has ended.
- *
- * @param {string} [url] Address a request was redirected to.
- *
- * @return {boolean} Whether the address is the login page.
- */
-function isLoginPage( url ) {
-	try {
-		return new URL( url ).pathname.endsWith( '/wp-login.php' );
-	} catch {
-		return false;
-	}
-}
-
 /**
  * Builds the arguments for a success notification dispatch.
  *
@@ -174,13 +154,10 @@ export function getNotificationArgumentsForSaveFail( data ) {
 			: messages.default;
 
 	if ( options?.isAutosave ) {
-		if ( error.code === 'fetch_error' ) {
-			noticeMessage = AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE;
-		} else if ( isLoginPage( error.data?.url ) ) {
-			noticeMessage = AUTO_SAVE_LOGGED_OUT_FAILURE_NOTICE;
-		} else {
-			noticeMessage = AUTO_SAVE_FAILURE_NOTICE;
-		}
+		noticeMessage =
+			error.code === 'fetch_error'
+				? AUTO_SAVE_NO_RESPONSE_FAILURE_NOTICE
+				: AUTO_SAVE_FAILURE_NOTICE;
 	}
 
 	return [ noticeMessage, { id } ];
diff --git a/packages/editor/src/store/utils/test/notice-builder.js b/packages/editor/src/store/utils/test/notice-builder.js
index 72a2d46ddc5486..244baa47b3b94b 100644
--- a/packages/editor/src/store/utils/test/notice-builder.js
+++ b/packages/editor/src/store/utils/test/notice-builder.js
@@ -168,20 +168,6 @@ describe( 'getNotificationArgumentsForSaveFail()', () => {
 			],
 			{ isAutosave: true },
 		],
-		[
-			'when the autosave was redirected to the login page',
-			'invalid_json',
-			[ 'publish', 'publish' ],
-			[
-				'Auto-save failed because you may have been logged out.',
-				{ id: 'editor-autosave' },
-			],
-			{ isAutosave: true },
-			{
-				status: 200,
-				url: 'http://example.com/wp-login.php?redirect_to=x',
-			},
-		],
 	].forEach(
 		( [
 			description,
@@ -189,12 +175,10 @@ describe( 'getNotificationArgumentsForSaveFail()', () => {
 			[ postStatus, editsStatus ],
 			expectedValue,
 			options = {},
-			data,
 		] ) => {
 			it( description, () => {
 				post.status = postStatus;
 				error.code = errorCode;
-				error.data = data;
 				edits.status = editsStatus;
 				expect(
 					getNotificationArgumentsForSaveFail( {
diff --git a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
index a9b91b0636eeb5..fa04e9f931751b 100644
--- a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
+++ b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
@@ -5,9 +5,6 @@ const {
 
 const AUTOSAVE_FAILED = 'Auto-save failed. You can also save manually.';
 
-const AUTOSAVE_FAILED_LOGGED_OUT =
-	'Auto-save failed because you may have been logged out.';
-
 const AUTOSAVE_FAILED_NO_RESPONSE =
 	'Auto-save failed because there was no response from the server. You can also save manually.';
 
@@ -112,7 +109,8 @@ test.describe( 'Autosave failure notice', () => {
 			'dropped-connection',
 			AUTOSAVE_FAILED_NO_RESPONSE,
 		],
-		[ 'error without a message', 'no-message', withDetails( 'Error 500' ) ],
+		// TODO: Show the status code.
+		[ 'error without a message', 'no-message', AUTOSAVE_FAILED ],
 		[
 			'error with a plain text message',
 			'plain-message',
@@ -144,10 +142,11 @@ test.describe( 'Autosave failure notice', () => {
 			'fatal-error-displayed',
 			AUTOSAVE_FAILED,
 		],
+		// TODO: Say the session may have expired.
 		[
 			'redirected to the login page',
 			'redirect-to-login',
-			AUTOSAVE_FAILED_LOGGED_OUT,
+			AUTOSAVE_FAILED,
 		],
 		[
 			'redirected to another site',

From db6ec8e62959e4cb78723d2562db422736c890a9 Mon Sep 17 00:00:00 2001
From: ella <ella@automattic.com>
Date: Mon, 19 Oct 2026 17:57:44 -0700
Subject: [PATCH 4/6] Start the details with the error code

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 packages/editor/src/store/actions.js          | 24 +++++++++++++------
 .../src/store/test/actions.jsdom.test.js      |  6 ++---
 .../various/autosave-failure-notice.spec.js   | 20 +++++++++-------
 3 files changed, 31 insertions(+), 19 deletions(-)

diff --git a/packages/editor/src/store/actions.js b/packages/editor/src/store/actions.js
index 5f94c7d6e4a4d2..b058adfa885116 100644
--- a/packages/editor/src/store/actions.js
+++ b/packages/editor/src/store/actions.js
@@ -413,19 +413,29 @@ export const savePost =
 				// `data.error`, apart from the generic message WordPress shows.
 				const phpError = error.data?.error?.message;
 				const status = error.data?.status;
-				const details = [
+				const message =
 					error.message &&
 					! CLIENT_GENERATED_ERROR_CODES.includes( error.code )
 						? getFailureDetails( error.message )
-						: '',
-					typeof phpError === 'string' ? phpError.trim() : '',
-					Number.isInteger( status ) && status >= 400
+						: '';
+				let summary = message;
+				if ( Number.isInteger( status ) && status >= 400 ) {
+					summary = message
 						? sprintf(
+								/* translators: 1: HTTP status code, such as 500. 2: Error message. */
+								__( 'Error code %1$d: %2$s' ),
+								status,
+								message
+							)
+						: sprintf(
 								/* translators: %d: HTTP status code, such as 500. */
-								__( 'Error %d' ),
+								__( 'Error code %d' ),
 								status
-							)
-						: '',
+							);
+				}
+				const details = [
+					summary,
+					typeof phpError === 'string' ? phpError.trim() : '',
 				]
 					.filter( Boolean )
 					.join( '\n\n' );
diff --git a/packages/editor/src/store/test/actions.jsdom.test.js b/packages/editor/src/store/test/actions.jsdom.test.js
index 61b924f0fc5c0d..c028d7a48636f8 100644
--- a/packages/editor/src/store/test/actions.jsdom.test.js
+++ b/packages/editor/src/store/test/actions.jsdom.test.js
@@ -427,7 +427,7 @@ describe( 'Post actions', () => {
 						},
 					},
 				},
-				'There has been a critical error on this website.\n\nUncaught Error: Call to undefined function f() in /var/www/html/a.php:2\nStack trace:\n#0 {main}\n  thrown\n\nError 500',
+				'Error code 500: There has been a critical error on this website.\n\nUncaught Error: Call to undefined function f() in /var/www/html/a.php:2\nStack trace:\n#0 {main}\n  thrown',
 			],
 			[
 				'ignores a PHP error message that is not a string',
@@ -436,7 +436,7 @@ describe( 'Post actions', () => {
 					message: 'Server error.',
 					data: { status: 500, error: { message: [ 'unexpected' ] } },
 				},
-				'Server error.\n\nError 500',
+				'Error code 500: Server error.',
 			],
 			[
 				'shows the status of a response that is not JSON',
@@ -445,7 +445,7 @@ describe( 'Post actions', () => {
 					message: 'The response is not a valid JSON response.',
 					data: { status: 502 },
 				},
-				'Error 502',
+				'Error code 502',
 			],
 			[
 				'shows no details for a successful response that is not JSON',
diff --git a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
index fa04e9f931751b..bece26101456ba 100644
--- a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
+++ b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
@@ -85,7 +85,7 @@ test.describe( 'Autosave failure notice', () => {
 			// WordPress version, so only its start is checked.
 			withDetails(
 				expect.stringMatching(
-					/^There has been a critical error on this website\.\nLearn more about troubleshooting WordPress\. \(https:\/\/wordpress\.org\/documentation\/article\/faq-troubleshooting\/\)\n\nUncaught Error: Call to undefined function gutenberg_test_autosave_undefined_function\(\) in .+\nStack trace:\n#0 /
+					/^Error code 500: There has been a critical error on this website\.\nLearn more about troubleshooting WordPress\. \(https:\/\/wordpress\.org\/documentation\/article\/faq-troubleshooting\/\)\n\nUncaught Error: Call to undefined function gutenberg_test_autosave_undefined_function\(\) in .+\nStack trace:\n#0 /
 				)
 			),
 		],
@@ -93,14 +93,14 @@ test.describe( 'Autosave failure notice', () => {
 			'database connection lost',
 			'database-connection-lost',
 			withDetails(
-				'Error establishing a database connection\n\nError 500'
+				'Error code 500: Error establishing a database connection'
 			),
 		],
 		[
 			'error message containing a link',
 			'link-in-message',
 			withDetails(
-				'Blocked. Learn more (https://example.com).\n\nError 403'
+				'Error code 403: Blocked. Learn more (https://example.com).'
 			),
 		],
 		// TODO: Retry right away.
@@ -114,13 +114,15 @@ test.describe( 'Autosave failure notice', () => {
 		[
 			'error with a plain text message',
 			'plain-message',
-			withDetails( 'Something went wrong on the server.\n\nError 500' ),
+			withDetails(
+				'Error code 500: Something went wrong on the server.'
+			),
 		],
 		[
 			'permission denied',
 			'permission',
 			withDetails(
-				'Sorry, you are not allowed to edit this post.\n\nError 403'
+				'Error code 403: Sorry, you are not allowed to edit this post.'
 			),
 		],
 		// The error's `data` is the database error, so there is no status in it.
@@ -129,11 +131,11 @@ test.describe( 'Autosave failure notice', () => {
 			'database-write',
 			withDetails( 'Could not update post in the database.' ),
 		],
-		[ 'HTML error page', 'bad-gateway', withDetails( 'Error 502' ) ],
+		[ 'HTML error page', 'bad-gateway', withDetails( 'Error code 502' ) ],
 		[
 			'too many requests',
 			'too-many-requests',
-			withDetails( 'Error 429' ),
+			withDetails( 'Error code 429' ),
 		],
 		// The error is printed before the headers, so the status stays 200.
 		// TODO: Show the PHP error the response includes in `data.error`.
@@ -157,7 +159,7 @@ test.describe( 'Autosave failure notice', () => {
 			'maintenance mode',
 			'maintenance',
 			withDetails(
-				'Briefly unavailable for scheduled maintenance. Check back in a minute.\n\nError 503'
+				'Error code 503: Briefly unavailable for scheduled maintenance. Check back in a minute.'
 			),
 		],
 		// TODO: Report the failure; the autosave fails without a notice.
@@ -212,7 +214,7 @@ test.describe( 'Autosave failure notice', () => {
 		await autosaveFailure.autosave();
 		// TODO: Say the session expired and offer to log in again.
 		expect( await autosaveFailure.getNotices() ).toEqual( [
-			withDetails( 'Cookie check failed\n\nError 403' ),
+			withDetails( 'Error code 403: Cookie check failed' ),
 		] );
 	} );
 

From 5adf35847f6559e9a9b64d2511a39b60dfbe6df6 Mon Sep 17 00:00:00 2001
From: ella <ella@automattic.com>
Date: Mon, 19 Oct 2026 19:33:09 -0700
Subject: [PATCH 5/6] Add the status to error responses without data

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 packages/api-fetch/CHANGELOG.md               |  2 +-
 .../api-fetch/src/test/index.jsdom.test.js    | 22 +++++++++++++++++++
 packages/api-fetch/src/utils/response.ts      | 13 ++++++++++-
 .../various/autosave-failure-notice.spec.js   |  7 ++++--
 4 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/packages/api-fetch/CHANGELOG.md b/packages/api-fetch/CHANGELOG.md
index 1e26320480faf4..836856d9572b20 100644
--- a/packages/api-fetch/CHANGELOG.md
+++ b/packages/api-fetch/CHANGELOG.md
@@ -8,7 +8,7 @@
 
 ### Enhancements
 
--   Include the response's status as `data.status` in `invalid_json` errors ([#85157](https://github.com/WordPress/gutenberg/pull/85157)).
+-   Include the response's status as `data.status` in `invalid_json` errors, and in error responses that have no `data` ([#85157](https://github.com/WordPress/gutenberg/pull/85157)).
 
 ## 7.57.0 (2026-10-07)
 
diff --git a/packages/api-fetch/src/test/index.jsdom.test.js b/packages/api-fetch/src/test/index.jsdom.test.js
index cbbf614266a45c..38eda68cc2283a 100644
--- a/packages/api-fetch/src/test/index.jsdom.test.js
+++ b/packages/api-fetch/src/test/index.jsdom.test.js
@@ -131,6 +131,27 @@ describe( 'apiFetch', () => {
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'bad_request',
 			message: 'Bad Request',
+			data: { status: 400 },
+		} );
+	} );
+
+	it( 'should keep the data of an error response', async () => {
+		globalThis.fetch.mockResolvedValue( {
+			ok: false,
+			status: 500,
+			async json() {
+				return {
+					code: 'db_update_error',
+					message: 'Could not update post in the database.',
+					data: 'Table does not exist',
+				};
+			},
+		} );
+
+		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
+			code: 'db_update_error',
+			message: 'Could not update post in the database.',
+			data: 'Table does not exist',
 		} );
 	} );
 
@@ -361,6 +382,7 @@ describe( 'apiFetch', () => {
 
 		await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( {
 			code: 'rest_cookie_invalid_nonce',
+			data: { status: 403 },
 		} );
 	} );
 
diff --git a/packages/api-fetch/src/utils/response.ts b/packages/api-fetch/src/utils/response.ts
index ff1d6641a1ff61..9ff3e0716a8ee3 100644
--- a/packages/api-fetch/src/utils/response.ts
+++ b/packages/api-fetch/src/utils/response.ts
@@ -76,5 +76,16 @@ export async function parseAndThrowError(
 	}
 
 	// Parse the response JSON and throw it as an error.
-	throw await parseJsonAndNormalizeError( response );
+	const error = await parseJsonAndNormalizeError( response );
+
+	// Like WordPress's own REST errors, an error carries its status in `data`.
+	if (
+		error &&
+		typeof error === 'object' &&
+		! Array.isArray( error ) &&
+		error.data === undefined
+	) {
+		throw { ...error, data: { status: response.status } };
+	}
+	throw error;
 }
diff --git a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
index bece26101456ba..c23012070927cd 100644
--- a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
+++ b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
@@ -109,8 +109,11 @@ test.describe( 'Autosave failure notice', () => {
 			'dropped-connection',
 			AUTOSAVE_FAILED_NO_RESPONSE,
 		],
-		// TODO: Show the status code.
-		[ 'error without a message', 'no-message', AUTOSAVE_FAILED ],
+		[
+			'error without a message',
+			'no-message',
+			withDetails( 'Error code 500' ),
+		],
 		[
 			'error with a plain text message',
 			'plain-message',

From 5a0d38424ec714f207acf721aa6ada566807bab8 Mon Sep 17 00:00:00 2001
From: ella <ella@automattic.com>
Date: Mon, 19 Oct 2026 20:35:04 -0700
Subject: [PATCH 6/6] Use one "Error code N." sentence before the message

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 packages/editor/src/store/actions.js          | 21 ++++++++-----------
 .../src/store/test/actions.jsdom.test.js      |  6 +++---
 .../various/autosave-failure-notice.spec.js   | 20 +++++++++---------
 3 files changed, 22 insertions(+), 25 deletions(-)

diff --git a/packages/editor/src/store/actions.js b/packages/editor/src/store/actions.js
index b058adfa885116..4e09dc925b92ef 100644
--- a/packages/editor/src/store/actions.js
+++ b/packages/editor/src/store/actions.js
@@ -418,21 +418,18 @@ export const savePost =
 					! CLIENT_GENERATED_ERROR_CODES.includes( error.code )
 						? getFailureDetails( error.message )
 						: '';
-				let summary = message;
-				if ( Number.isInteger( status ) && status >= 400 ) {
-					summary = message
+				const summary = [
+					Number.isInteger( status ) && status >= 400
 						? sprintf(
-								/* translators: 1: HTTP status code, such as 500. 2: Error message. */
-								__( 'Error code %1$d: %2$s' ),
-								status,
-								message
-							)
-						: sprintf(
 								/* translators: %d: HTTP status code, such as 500. */
-								__( 'Error code %d' ),
+								__( 'Error code %d.' ),
 								status
-							);
-				}
+							)
+						: '',
+					message,
+				]
+					.filter( Boolean )
+					.join( ' ' );
 				const details = [
 					summary,
 					typeof phpError === 'string' ? phpError.trim() : '',
diff --git a/packages/editor/src/store/test/actions.jsdom.test.js b/packages/editor/src/store/test/actions.jsdom.test.js
index c028d7a48636f8..0edc02a8d08eda 100644
--- a/packages/editor/src/store/test/actions.jsdom.test.js
+++ b/packages/editor/src/store/test/actions.jsdom.test.js
@@ -427,7 +427,7 @@ describe( 'Post actions', () => {
 						},
 					},
 				},
-				'Error code 500: There has been a critical error on this website.\n\nUncaught Error: Call to undefined function f() in /var/www/html/a.php:2\nStack trace:\n#0 {main}\n  thrown',
+				'Error code 500. There has been a critical error on this website.\n\nUncaught Error: Call to undefined function f() in /var/www/html/a.php:2\nStack trace:\n#0 {main}\n  thrown',
 			],
 			[
 				'ignores a PHP error message that is not a string',
@@ -436,7 +436,7 @@ describe( 'Post actions', () => {
 					message: 'Server error.',
 					data: { status: 500, error: { message: [ 'unexpected' ] } },
 				},
-				'Error code 500: Server error.',
+				'Error code 500. Server error.',
 			],
 			[
 				'shows the status of a response that is not JSON',
@@ -445,7 +445,7 @@ describe( 'Post actions', () => {
 					message: 'The response is not a valid JSON response.',
 					data: { status: 502 },
 				},
-				'Error code 502',
+				'Error code 502.',
 			],
 			[
 				'shows no details for a successful response that is not JSON',
diff --git a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
index c23012070927cd..5da62979b95481 100644
--- a/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
+++ b/test/e2e/specs/editor/various/autosave-failure-notice.spec.js
@@ -85,7 +85,7 @@ test.describe( 'Autosave failure notice', () => {
 			// WordPress version, so only its start is checked.
 			withDetails(
 				expect.stringMatching(
-					/^Error code 500: There has been a critical error on this website\.\nLearn more about troubleshooting WordPress\. \(https:\/\/wordpress\.org\/documentation\/article\/faq-troubleshooting\/\)\n\nUncaught Error: Call to undefined function gutenberg_test_autosave_undefined_function\(\) in .+\nStack trace:\n#0 /
+					/^Error code 500\. There has been a critical error on this website\.\nLearn more about troubleshooting WordPress\. \(https:\/\/wordpress\.org\/documentation\/article\/faq-troubleshooting\/\)\n\nUncaught Error: Call to undefined function gutenberg_test_autosave_undefined_function\(\) in .+\nStack trace:\n#0 /
 				)
 			),
 		],
@@ -93,14 +93,14 @@ test.describe( 'Autosave failure notice', () => {
 			'database connection lost',
 			'database-connection-lost',
 			withDetails(
-				'Error code 500: Error establishing a database connection'
+				'Error code 500. Error establishing a database connection'
 			),
 		],
 		[
 			'error message containing a link',
 			'link-in-message',
 			withDetails(
-				'Error code 403: Blocked. Learn more (https://example.com).'
+				'Error code 403. Blocked. Learn more (https://example.com).'
 			),
 		],
 		// TODO: Retry right away.
@@ -112,20 +112,20 @@ test.describe( 'Autosave failure notice', () => {
 		[
 			'error without a message',
 			'no-message',
-			withDetails( 'Error code 500' ),
+			withDetails( 'Error code 500.' ),
 		],
 		[
 			'error with a plain text message',
 			'plain-message',
 			withDetails(
-				'Error code 500: Something went wrong on the server.'
+				'Error code 500. Something went wrong on the server.'
 			),
 		],
 		[
 			'permission denied',
 			'permission',
 			withDetails(
-				'Error code 403: Sorry, you are not allowed to edit this post.'
+				'Error code 403. Sorry, you are not allowed to edit this post.'
 			),
 		],
 		// The error's `data` is the database error, so there is no status in it.
@@ -134,11 +134,11 @@ test.describe( 'Autosave failure notice', () => {
 			'database-write',
 			withDetails( 'Could not update post in the database.' ),
 		],
-		[ 'HTML error page', 'bad-gateway', withDetails( 'Error code 502' ) ],
+		[ 'HTML error page', 'bad-gateway', withDetails( 'Error code 502.' ) ],
 		[
 			'too many requests',
 			'too-many-requests',
-			withDetails( 'Error code 429' ),
+			withDetails( 'Error code 429.' ),
 		],
 		// The error is printed before the headers, so the status stays 200.
 		// TODO: Show the PHP error the response includes in `data.error`.
@@ -162,7 +162,7 @@ test.describe( 'Autosave failure notice', () => {
 			'maintenance mode',
 			'maintenance',
 			withDetails(
-				'Error code 503: Briefly unavailable for scheduled maintenance. Check back in a minute.'
+				'Error code 503. Briefly unavailable for scheduled maintenance. Check back in a minute.'
 			),
 		],
 		// TODO: Report the failure; the autosave fails without a notice.
@@ -217,7 +217,7 @@ test.describe( 'Autosave failure notice', () => {
 		await autosaveFailure.autosave();
 		// TODO: Say the session expired and offer to log in again.
 		expect( await autosaveFailure.getNotices() ).toEqual( [
-			withDetails( 'Error code 403: Cookie check failed' ),
+			withDetails( 'Error code 403. Cookie check failed' ),
 		] );
 	} );