Over the past two days,I have repeatefly encountered response-stream falures in ChatGPT Projects while using GPT-5.6 Sol High.
The main problem is “Error in message stream.” In several cases, a response made substantial progress and appeared to be reasoning normally, but was cut off partway through. I have also encountered related failures such as “Something went wrong,” “Thinking Failed,” connection interruptions, or message-delivery timeouts.
Starting a branch did not resolve the problem. In the affected branch, three attempts at a complex text request produced very different results:
The first attempt produced a complete response, but it conflicted with previously established conversation context.
The second attempt replied almost immediately with only an acknowledgement that the task would be completed, but did not perform the requested work.
After regenerating, the third attempt visibly reasoned for approximately two minutes and produced a much more context-aware response, but the answer was cut off halfway with “Error in message stream.”
Other newly created chats inside the same Project have also shown errors. However, Work remains usable on the same account, and comparable tasks can still complete there.
The affected conversations are not exceptionally long by message count: one had approximately 16 messages when the stream error occurred, while the branch had approximately 35. This does not appear to be explained solely by a conversation naturally reaching an extreme length.
Expected behavior: Project chats and branches should complete responses consistently and preserve the context available before the branch point.
Actual behavior: reasoning depth, context application, task execution, and response streaming vary significantly between retries, with some responses stopping before execution and others failing after substantial progress.
Has anyone else reprodeced thie specifically in Projects or branched chats while Work continues to function normally?
I noticed this today too! I haven’t tried it in any other project folders, but it’s really annoying that I can’t use my custom project instructions and context for what I’m working on.
Also, my phone and computer are showing the same error. I updated the app on my phone, restarted the app multiple times, logged out and back in, and turned off my wifi (all suggestions from Google regarding this error).
Thanks — your cross-device result is useful. It makes a purely browser-specific explanation less likely.
For me, this has been ongoing for roughly the past two days. I have only tested the web version on desktop, so I cannot cannot confirm whether the same issue occurs in the mobile app.
The problem is concentrated around Project chats and branched conversations. Longer generation attempts can begin normally, then stop mid-response with “Error in message stream.” Some retries instead return an immediate acknowledgement or plan without actually completing the requested work.
Things I have already tried:
refreshing and reopening the conversation;
clearing browser cache;
starting new chats;
branching from an earlier point;
moving work to a new Project;
comparing the same kind of task in Work mode.
The behavior is inconsistent: some attempts produce a complete but context-conflicting response, some give a near-instant “I’ll handle it” response without execution, and some begin a longer, more context-aware response before failing in the message stream.
I’m seeing a very similar issue today, but in my case it appears isolated to a single Project.
Chats outside that Project work normally. Inside the affected Project, however, every existing chat and every newly created chat fails with either “Error in message stream” or “Something went wrong,” even for a simple prompt such as “hi”.
I reproduced the same behavior in an incognito browser session, so it does not appear to be browser-session specific.
I can also identify exactly when it started. The Project was working normally until I pasted an image directly into one of its chats and submitted the message. The image upload did not complete, and from that point onward the entire Project became unusable.
I deleted the conversation in which that happened, but that did not resolve it. Newly created chats inside the same Project still fail immediately.
I can’t say that the failed image upload caused the issue, but the timing was exact. This makes me wonder whether a failed attachment transaction or Project-level context/indexing state can leave a Project in a bad backend state.
I’m avoiding deleting or recreating the Project because it contains important Project Sources and accumulated context.
Getting same issue on project chats. Using Chatgpt on mobile app. New chats work fine. I need to use my project due to the sources. Anyone looking into this from @OpenAI_Support ?
I have the same issue on one project, fails on both browser and mobile app. It started with only new chats/branches having the issue but now its every chat in my project failing to generate a response.