withastro · ematipico · Apr 16, 2026 · Apr 16, 2026 · Apr 16, 2026
diff --git a/.changeset/afraid-coins-wear.md b/.changeset/afraid-coins-wear.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes an issue where build output files could contain special characters (`!`, `~`, `{`, `}`) in their names, causing deploy failures on platforms like Netlify.
diff --git a/packages/astro/src/core/build/static-build.ts b/packages/astro/src/core/build/static-build.ts
@@ -32,7 +32,7 @@ import {
 } from './plugins/plugin-ssr.js';
 import { ASTRO_PAGE_EXTENSION_POST_PATTERN } from './plugins/util.js';
 import type { StaticBuildOptions } from './types.js';
-import { encodeName, getTimeStat, viteBuildReturnToRollupOutputs } from './util.js';
+import { cleanChunkName, getTimeStat, viteBuildReturnToRollupOutputs } from './util.js';
 import { NOOP_MODULE_ID } from './plugins/plugin-noop.js';
 import { ASTRO_VITE_ENVIRONMENT_NAMES } from '../constants.js';
 import type { InputOption } from 'rollup';
@@ -280,15 +280,14 @@ async function buildEnvironments(opts: StaticBuildOptions, internals: BuildInter
 						// TODO: refactor our build logic to avoid this
 						if (name.includes(ASTRO_PAGE_EXTENSION_POST_PATTERN)) {
 							const [sanitizedName] = name.split(ASTRO_PAGE_EXTENSION_POST_PATTERN);
-							return [prefix, sanitizedName, suffix].join('');
+							return [prefix, cleanChunkName(sanitizedName), suffix].join('');
 						}
 						// Injected routes include "pages/[name].[ext]" already. Clean those up!
 						if (name.startsWith('pages/')) {
 							const sanitizedName = name.split('.')[0];
-							return [prefix, sanitizedName, suffix].join('');
+							return [prefix, cleanChunkName(sanitizedName), suffix].join('');
 						}
-						const encoded = encodeName(name);
-						return [prefix, encoded, suffix].join('');
+						return [prefix, cleanChunkName(name), suffix].join('');
 					},
 					assetFileNames: `${settings.config.build.assets}/[name].[hash][extname]`,
 					...viteConfig.build?.rollupOptions?.output,
@@ -419,8 +418,12 @@ async function buildEnvironments(opts: StaticBuildOptions, internals: BuildInter
 					rollupOptions: {
 						preserveEntrySignatures: 'exports-only',
 						output: {
-							entryFileNames: `${settings.config.build.assets}/[name].[hash].js`,
-							chunkFileNames: `${settings.config.build.assets}/[name].[hash].js`,
+							entryFileNames(chunkInfo) {
+								return `${settings.config.build.assets}/${cleanChunkName(chunkInfo.name)}.[hash].js`;
+							},
+							chunkFileNames(chunkInfo) {
+								return `${settings.config.build.assets}/${cleanChunkName(chunkInfo.name)}.[hash].js`;
+							},
 							assetFileNames: `${settings.config.build.assets}/[name].[hash][extname]`,
 							...viteConfig.environments?.client?.build?.rollupOptions?.output,
 						},

diff --git a/packages/astro/src/core/build/util.ts b/packages/astro/src/core/build/util.ts
@@ -31,7 +31,23 @@ export function shouldAppendForwardSlash(
 	}
 }
 
-export function encodeName(name: string): string {
+/**
+ * Matches any character that is NOT alphanumeric, underscore, dot, hyphen, or forward slash.
+ * Rollup's built-in `sanitizeFileName` misses characters like `!` and `~` that can leak
+ * from Vite module IDs into chunk names (e.g. `page.!{005}.js`).
+ */
+const UNSAFE_CHUNK_CHAR_RE = /[^\w.\-/]/g;
+
+/**
+ * Replaces characters in a chunk name that are not safe for filesystem paths or URLs.
+ * Characters like `!` and `~` can leak from Vite module IDs into Rollup chunk names
+ * and break deploys on platforms like Netlify.
+ */
+export function cleanChunkName(name: string): string {
+	return encodeName(name.replace(UNSAFE_CHUNK_CHAR_RE, '_'));
+}
+
+function encodeName(name: string): string {
 	// Detect if the chunk name has as % sign that is not encoded.
 	// This is borrowed from Node core: https://github.com/nodejs/node/blob/3838b579e44bf0c2db43171c3ce0da51eb6b05d5/lib/internal/url.js#L1382-L1391
 	// We do this because you cannot import a module with this character in it.

diff --git a/packages/astro/test/fixtures/ssr-script/src/pages/dynamic.astro b/packages/astro/test/fixtures/ssr-script/src/pages/dynamic.astro
@@ -0,0 +1,11 @@
+<html>
+	<head>
+		<title>Dynamic import</title>
+	</head>
+	<body>
+		<h1>Dynamic import</h1>
+		<script>
+			import('../scripts/confetti.js').then(m => m.celebrate());
+		</script>
+	</body>
+</html>
diff --git a/packages/astro/test/fixtures/ssr-script/src/scripts/confetti.js b/packages/astro/test/fixtures/ssr-script/src/scripts/confetti.js
@@ -0,0 +1,3 @@
+export function celebrate() {
+	console.log('confetti!');
+}
diff --git a/packages/astro/test/special-chars-in-component-imports.test.js b/packages/astro/test/special-chars-in-component-imports.test.js
@@ -33,6 +33,18 @@ describe('Special chars in component import paths', () => {
 			assert.equal(html.includes('<html>'), true);
 		});
 
+		it('Output JS filenames do not contain unsafe characters', async () => {
+			const files = await fixture.readdir('/_astro');
+			const jsFiles = files.filter((f) => f.endsWith('.js'));
+			for (const file of jsFiles) {
+				assert.equal(
+					/[!~#{}<>]/.test(file),
+					false,
+					`File "${file}" contains unsafe characters that break some hosting platforms`,
+				);
+			}
+		});
+
 		it('Special chars in imports work from .astro files', async () => {
 			const html = await fixture.readFile('/index.html');
 			const $ = cheerioLoad(html);

diff --git a/packages/astro/test/ssr-script.test.js b/packages/astro/test/ssr-script.test.js
@@ -37,6 +37,45 @@ describe('Inline scripts in SSR', () => {
 			const $ = cheerioLoad(html);
 			assert.equal($('script').length, 1);
 		});
+
+		it('server output filenames do not contain unsafe characters', async () => {
+			const files = await fixture.glob('server/**/*.{js,mjs}');
+			for (const file of files) {
+				assert.equal(
+					/[!~#{}<>]/.test(file),
+					false,
+					`File "${file}" contains characters that break hosting platforms like Netlify`,
+				);
+			}
+		});
+	});
+
+	describe('with assetQueryParams', () => {
+		before(async () => {
+			fixture = await loadFixture({
+				...defaultFixtureOptions,
+				outDir: './dist/inline-scripts-with-asset-query-params',
+				adapter: testAdapter({
+					extendAdapter: {
+						client: {
+							assetQueryParams: new URLSearchParams({ dpl: 'test123' }),
+						},
+					},
+				}),
+			});
+			await fixture.build();
+		});
+
+		it('client output filenames do not contain hash placeholders or unsafe characters', async () => {
+			const files = await fixture.glob('client/**/*.{js,mjs}');
+			for (const file of files) {
+				assert.equal(
+					/[!~{}]/.test(file),
+					false,
+					`File "${file}" contains unsafe characters (likely unresolved hash placeholders)`,
+				);
+			}
+		});
 	});
 
 	describe('with base path', () => {

diff --git a/packages/astro/test/units/build/static-build.test.ts b/packages/astro/test/units/build/static-build.test.ts
@@ -1,9 +1,33 @@
 import * as assert from 'node:assert/strict';
 import { describe, it } from 'node:test';
 import { makeAstroPageEntryPointFileName } from '../../../dist/core/build/static-build.js';
+import { cleanChunkName } from '../../../dist/core/build/util.js';
 import type { RouteData } from '../../../dist/types/public/internal.js';
 
 describe('astro/src/core/build', () => {
+	describe('cleanChunkName', () => {
+		it('passes through safe names unchanged', () => {
+			assert.equal(cleanChunkName('page'), 'page');
+			assert.equal(cleanChunkName('my-component'), 'my-component');
+			assert.equal(cleanChunkName('pages/index'), 'pages/index');
+			assert.equal(cleanChunkName('chunk_abc123'), 'chunk_abc123');
+		});
+
+		it('replaces ! and ~ characters', () => {
+			assert.equal(cleanChunkName('page.!{005}'), 'page.__005_');
+			assert.equal(cleanChunkName('~something'), '_something');
+		});
+
+		it('replaces other unsafe characters', () => {
+			assert.equal(cleanChunkName('name@scope'), 'name_scope');
+			assert.equal(cleanChunkName('file#hash'), 'file_hash');
+		});
+
+		it('replaces % character', () => {
+			assert.equal(cleanChunkName('chunk%name'), 'chunk_name');
+		});
+	});
+
 	describe('makeAstroPageEntryPointFileName', () => {
 		const routes: RouteData[] = [
 			{