fix(responses): surface upstream error status on get instead of 500

[mateo-berri]

Relevant issues

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• My PR passes all CI/CD checks (e.g., lint, format, unit tests)
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Screenshots / Proof of Fix

Live proxy against a real Azure OpenAI deployment (azure/gpt-4o, api_version 2025-03-01-preview), run with .venv/bin/python litellm/proxy/proxy_cli.py --config config.yaml --port 29764 --detailed_debug

Before, on litellm_internal_staging @ 7f991481cc069d7a069a8a50c140bcfaec9a4e6c. Create a non-retrievable response, then GET it

curl -s http://localhost:29764/v1/responses \
  -H "Authorization: Bearer sk-fix4-local" -H "Content-Type: application/json" \
  -d '{"model":"azure-responses-test","input":"ping","store":false}'
# 200, id resp_LOQEeaPx46R3...

curl -s -w "\nHTTP_STATUS:%{http_code}\n" http://localhost:29764/v1/responses/resp_LOQEeaPx46R3... \
  -H "Authorization: Bearer sk-fix4-local"

{"error":{"message":"litellm.APIConnectionError: AzureException APIConnectionError - 3 validation errors for ResponsesAPIResponse\nid\n  Field required [type=missing, input_value={'error': {'message': \"Re...m': None, 'code': None}}, input_type=dict]\n ...","type":null,"param":null,"code":"500"}}
HTTP_STATUS:500

Same on a deleted id: POST with "store": true, DELETE it (200 response.deleted), then GET the deleted id returns the identical 500 pydantic ValidationError. Control: POST stored + GET returns 200

After, on fd9d0cf3f6ff9e718a5e172c17ad485f536a1fa2. Same two error curls now surface the real upstream status and message

curl -s -w "\nHTTP_STATUS:%{http_code}\n" http://localhost:29764/v1/responses/resp_04fd61c97344... \
  -H "Authorization: Bearer sk-fix4-local"

{"error":{"message":"litellm.NotFoundError: AzureException NotFoundError - {\n  \"error\": {\n    \"message\": \"Response with id 'resp_04fd61c97344f4f8016a4c26fa6fcc819391ced2af096216ae' not found.\",\n    \"type\": \"invalid_request_error\",\n    \"param\": null,\n    \"code\": null\n  }\n} ...","type":null,"param":null,"code":"404"}}
HTTP_STATUS:404

GET on a deleted id likewise returns 404 with Azure's "Response with id ... not found." message. The stored control still returns 200 with the full response, and DELETE still returns 200

Type

🐛 Bug Fix

Changes

GET /v1/responses/{id} returned a 500 APIConnectionError whenever the upstream provider returned an error (response created with "store": false, or id already deleted). Root cause: HTTPHandler.get / AsyncHTTPHandler.get never call raise_for_status() (unlike post and delete), so the upstream error JSON flowed into transform_get_response_api_response, which force-parsed it into the ResponsesAPIResponse pydantic model and blew up with ValidationError: 3 validation errors ... id/created_at/output Field required

llm_http_handler.py: the four responses GET call sites (get_responses, async_get_responses, list_responses_input_items, async_list_responses_input_items) now call response.raise_for_status() inside the existing try, so upstream errors route through _handle_error and the provider error class with their real status and body, matching what create/cancel (POST) and delete already do

exception_mapping_utils.py: the azure mapper had no 404 branch in its status ladder, and its "invalid_request_error" in error_str string match ran before any status check, downgrading Azure's 404 (which carries "type": "invalid_request_error") to a 400. Added the 404 branch raising NotFoundError and gated the string match to status 400 or no status, so real statuses survive the mapping

Regression tests in the mapped test files: tests/test_litellm/llms/custom_httpx/test_llm_http_handler.py covers async GET, sync GET, and input items surfacing a 404 NotFoundError (dependency-injected client backed by httpx.MockTransport), and tests/test_litellm/litellm_core_utils/test_exception_mapping_utils.py pins azure 404 + invalid_request_error mapping to NotFoundError. All four tests fail on the pre-fix code and pass with the fix

[mateo-berri]

@greptileai

[greptile-apps]

Greptile Summary

This PR fixes GET /v1/responses/{id} (and GET .../input_items) surfacing a 500 APIConnectionError instead of the real upstream error. The root cause was two missing pieces: GET paths never called raise_for_status(), and the Azure exception mapper unconditionally matched "invalid_request_error" (present in Azure 404 bodies) before checking the HTTP status code.

• llm_http_handler.py: response.raise_for_status() added to all four GET call sites (sync/async get_responses and list_responses_input_items), matching the existing pattern already used by the POST/DELETE paths; also demotes verbose_logger.exception to verbose_logger.debug for expected upstream errors.
• exception_mapping_utils.py: The "invalid_request_error" string-match branch is now gated to status_code in (None, 400), and a dedicated 404 → NotFoundError branch is added to the Azure status-code ladder so real 404s are no longer silently downgraded to BadRequestError.
• Tests: All four changed GET paths are covered by new mock-transport tests, plus a direct unit test for the Azure 404 exception-mapping fix; no real network calls are made.

Confidence Score: 5/5

Safe to merge — changes are narrowly scoped to four GET call sites and one Azure exception-mapping branch, with mock-transport tests covering each modified path.

The fix correctly applies raise_for_status() to align GET with the existing post/delete pattern, and the exception-mapping change is carefully gated so only the 400/None ambiguous case falls back to string-matching while real status codes (404, 429, 500 etc.) go through the status-code ladder. All four call sites have regression tests. No existing behavior is broken for successful (2xx) responses.

No files require special attention.

Important Files Changed

Filename	Overview
litellm/llms/custom_httpx/llm_http_handler.py	Adds response.raise_for_status() to all four GET call sites (sync/async get_responses and list_responses_input_items), matching the existing post/delete pattern; also correctly demotes the async_get_responses log from exception to debug.
litellm/litellm_core_utils/exception_mapping_utils.py	Gates the "invalid_request_error" string-match branch to status_code in (None, 400) and adds a dedicated 404 branch in the Azure status-code ladder, fixing Azure 404s being incorrectly downgraded to BadRequestError.
tests/test_litellm/llms/custom_httpx/test_llm_http_handler.py	Adds mock-transport tests covering all four changed GET paths (async and sync get_responses, async and sync list_input_items); uses httpx.MockTransport to avoid real network calls, consistent with repo test rules.
tests/test_litellm/litellm_core_utils/test_exception_mapping_utils.py	Adds a regression test pinning Azure 404 + invalid_request_error body to NotFoundError, exercising the updated _map_azure_exception branch directly.

_{Reviews (3): Last reviewed commit: "fix(responses): demote expected 4xx get ..." | Re-trigger Greptile}

[greptile-apps]

Greptile Summary

This PR fixes GET /v1/responses/{id} returning a 500 APIConnectionError whenever the upstream provider returned an error, by adding response.raise_for_status() to all four GET call sites in llm_http_handler.py so HTTP errors are routed through _handle_error instead of falling through to the pydantic transformer. It also fixes the Azure exception mapper, which was downgrading real 404 responses to BadRequestError because their "invalid_request_error" type field hit a string-match branch before the status-code ladder.

• llm_http_handler.py: four raise_for_status() calls added to get_responses (sync + async) and list_responses_input_items (sync + async); upstream HTTP errors now follow the same _handle_error path as POST/DELETE already did.
• exception_mapping_utils.py: added a 404 branch to the Azure status-code ladder and gated the "invalid_request_error" string match to status 400 or unset, so 404s with that error type correctly raise NotFoundError.
• New mock-transport unit tests cover async GET, sync GET, and async list-input-items; the sync list_responses_input_items path is the only one without a dedicated new test.

Confidence Score: 4/5

The change is narrow, well-tested, and fixes a real regression without touching any auth or critical-path logic.

Both changes are straightforward: adding raise_for_status() to GET handlers and inserting a 404 branch in the Azure exception mapper. The logic is correct, the mock tests verify the end-to-end mapping, and the fix is isolated to the Responses API GET paths. The only friction is that async_get_responses still logs expected 4xx errors at exception level, which will add stack-trace noise to production logs for normal client errors like 'response not found'.

llm_http_handler.py around the async_get_responses exception handler — the pre-existing verbose_logger.exception call will now emit stack traces for ordinary 404 responses.

Important Files Changed

Filename	Overview
litellm/llms/custom_httpx/llm_http_handler.py	Adds response.raise_for_status() to four GET call sites so upstream HTTP errors route through _handle_error instead of reaching the pydantic transformer and exploding as ValidationError; async get_responses will now also emit a verbose_logger.exception stack trace for expected 4xx errors.
litellm/litellm_core_utils/exception_mapping_utils.py	Adds a 404 branch to the Azure status-code ladder and gates the "invalid_request_error" string match to status 400/None, preventing Azure 404s (which carry "type": "invalid_request_error") from being downgraded to BadRequestError.
tests/test_litellm/llms/custom_httpx/test_llm_http_handler.py	New mock-transport tests verify async GET, sync GET, and async list-input-items surface NotFoundError on 404; sync list_responses_input_items path is untested.
tests/test_litellm/litellm_core_utils/test_exception_mapping_utils.py	Adds a focused unit test pinning Azure 404 + invalid_request_error body to NotFoundError with correct status code; straightforward and correct.

_{Reviews (2): Last reviewed commit: "fix(responses): surface upstream error s..." | Re-trigger Greptile}

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Codecov Report

✅ All modified and coverable lines are covered by tests.

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[mateo-berri]

@greptileai