LibreChat/api
Helge Wiethoff 61b9b1daa7
🩹 fix(SSE): Treat responseCode === 0 as Transport Failure, Not Server Error (#12834)
* fix(sse): treat responseCode===0 as transport failure, not server error

When a long-running model response (e.g. gpt-5.4 with web_search:true)
takes longer than the browser's idle connection timeout, the SSE transport
drops and sse.js fires an error event with responseCode=0 and e.data set
to the raw response buffer (non-JSON SSE text).

The previous guard `!responseCode` is truthy for both 0 (transport drop)
and undefined (genuine server-sent error event), so the client incorrectly
entered the server-error branch, tried to JSON.parse raw SSE text, logged
"Failed to parse server error", and showed the user a red error banner --
even though the backend continued processing and delivered the final answer
seconds later.

Fix 1 (client): change guard from `!responseCode` to `responseCode == null`
so that only undefined/null (no HTTP status at all) triggers the server-error
parse path. responseCode===0 now correctly falls through to the reconnect path.

Fix 2 (backend): after res.flushHeaders() the response is already committed
as SSE. The fallback branch that wrote res.status(404).json() was an HTTP/SSE
protocol violation. Replace with an SSE-conformant event:error frame + res.end().

* fix(sse): use onError helper on subscribe failure + add regression tests

Replace silent res.end() with onError('Failed to subscribe to stream')
so the client receives a parseable SSE error event instead of a stream
that closes with no signal. The previous res.end() left the UI stuck
in "submitting" state because no error/abort/final event ever fired.

Also adds two missing test cases for the responseCode guard change:
- responseCode === 0 with raw SSE buffer data must NOT call errorHandler
  (transport failure should reconnect, not display garbage)
- responseCode == null with JSON error data MUST call errorHandler
  (server-sent error events should still surface to the user)

---------

Co-authored-by: Danny Avila <danny@librechat.ai>
2026-04-29 10:05:51 +09:00
..
app 🌱 fix: Inject Code-Tool Files Into Graph Sessions on First Call (+ read_file Sandbox Fallback) (#12831) 2026-04-27 08:56:39 +09:00
cache 🚦 fix: ERR_ERL_INVALID_IP_ADDRESS and IPv6 Key Collisions in IP Rate Limiters (#12319) 2026-03-19 21:48:03 -04:00
config 🔊 fix: Preserve Log Metadata on Console for Warn/Error Levels (#12737) 2026-04-19 21:49:41 -07:00
db 🐛 fix: Resolve MeiliSearch Startup Sync Failure from Model Loading Order (#12397) 2026-03-25 14:02:44 -04:00
models 🗑️ chore: Remove Action Test Suite and Update Mock Implementations (#12268) 2026-03-21 14:28:55 -04:00
server 🩹 fix(SSE): Treat responseCode === 0 as Transport Failure, Not Server Error (#12834) 2026-04-29 10:05:51 +09:00
strategies 🔐 feat: Admin Auth Support for SAML and Social OAuth Providers (#12472) 2026-03-30 22:49:44 -04:00
test 🌱 fix: Inject Code-Tool Files Into Graph Sessions on First Call (+ read_file Sandbox Fallback) (#12831) 2026-04-27 08:56:39 +09:00
utils 🦉 feat: Claude Opus 4.7 Model Support (#12698) 2026-04-16 14:51:00 -04:00
jest.config.js 📏 refactor: Add File Size Limits to Conversation Imports (#12221) 2026-03-14 03:06:29 -04:00
jsconfig.json feat(api): initial Redis support; fix(SearchBar): proper debounce (#1039) 2023-10-11 17:05:47 -04:00
package.json 🌱 fix: Inject Code-Tool Files Into Graph Sessions on First Call (+ read_file Sandbox Fallback) (#12831) 2026-04-27 08:56:39 +09:00
typedefs.js 🪦 refactor: Remove Legacy Code (#10533) 2025-12-11 16:36:12 -05:00