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Chats become unusable after context compaction and print internal validation errors #41922
Description
What version of the Codex App are you using (From “About Codex” dialog)?
26.825.51511
What subscription do you have?
ChatGPT Plus
What platform is your computer?
Microsoft Windows NT 10.0.22621.0 x64
What issue are you seeing?
I am experiencing an issue where Codex App chats eventually become unusable when a context compaction occurs.
The problem first appeared around August 27. I was actively using Codex when my Windows PC experienced a BSOD. After restarting the computer, the chat I had been using became affected, and several other existing chats also started showing similar behavior. Not every existing chat was affected at that time.
The issue is now also affecting newly created chats. A new chat initially works normally, sometimes for a considerable amount of time. However, when the conversation reaches the point where Codex attempts to compact the context, the problem appears.
Instead of continuing the conversation normally after context compaction, Codex starts printing what appears to be internal structured data or validation information directly into the chat. The output contains brackets, field names, validation-related text such as "input" and "valid value", and fragments of code or other internal-looking data.
After this happens, sending additional messages does not restore normal behavior and the affected chat becomes effectively unusable.
I am using the latest available version of the Codex App and regularly check the application for updates, but the problem continues to occur.
What steps can reproduce the bug?
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Create a new chat in the Codex App.
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Use the chat normally and continue the conversation until enough context has accumulated for Codex to perform context compaction.
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When context compaction occurs, wait for Codex to continue the conversation.
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Instead of returning to normal conversation, the chat starts displaying internal-looking structured or validation data, including brackets, field names, validation-related text such as "input" and "valid value", and fragments of code or structured data.
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Send another message in the same chat.
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The chat continues exhibiting the same broken behavior and becomes effectively unusable.
The problem originally appeared after my computer experienced a BSOD while Codex was running. However, the issue is no longer limited to chats that existed at the time of the crash. Newly created chats can also develop the same problem once context compaction occurs.
What is the expected behavior?
Context compaction should complete normally and the conversation should remain usable afterward.
After compaction, Codex should continue responding to the user normally while retaining the relevant context needed to continue the session.
Internal validation information, structured error data, implementation details, or code related to the compaction process should not be printed directly into the conversation.
The chat should remain functional after context compaction.
Additional information
The issue first appeared around August 27 after my Windows PC experienced a BSOD while I was actively using the Codex App.
After restarting the computer, the chat that was active during the crash exhibited the problem. Several other existing chats also developed similar symptoms, although some chats remained functional.
Since then, I have confirmed that the issue is not limited to conversations that existed at the time of the BSOD. Newly created conversations initially work normally but can eventually develop the same problem when context compaction occurs.
I keep the Codex App updated and check for updates manually every day. I am currently running version 26.825.51511, and the problem continues to occur despite keeping the app fully up to date.
Before opening this report, I searched the GitHub repository for existing open issues describing similar symptoms. I commented on the relevant open issues I found. In one of those issues, I was informed that the previously reported problem had been fixed a few months ago and that, if similar symptoms were still occurring on the latest version, I should open a new bug report. That issue was then closed.
I am therefore opening this new report because I am still experiencing the problem on the current version of the Codex App.
@etraut-openai asked me to open this issue on #27269, #27555 and #27511.
Activity
github-actions commentedon Aug 31, 2026
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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coppolaop commentedon Aug 31, 2026
coppolaop commentedon Sep 3, 2026
I updated today and the second message on a new chat returned me this message:
coppolaop commentedon Sep 4, 2026
v26.901.31953
coppolaop commentedon Sep 5, 2026
I started using a new chat in my project yesterday and it was working normally. Today, after another request triggered context compaction, the issue happened again. The error message has changed between app versions, but the underlying problem is still present.
I’m a paying user and I still cannot reliably use the app because chats keep becoming unusable after compaction. This is becoming very frustrating, as I’m continuing to pay for a service that I currently cannot depend on.
coppolaop commentedon Sep 5, 2026
As a temporary workaround, I’ve been creating a new chat every time context compaction breaks the current one. This forces me to repeatedly re-explain the project context and continue the same work across multiple chats, which significantly increases token usage.
For a relatively small feature, I had to use 3–4 different chats and exhausted my entire 5-hour allowance. Since token usage has a real cost, having to spend so much extra usage just to work around this issue is becoming increasingly frustrating.
coppolaop commentedon Sep 6, 2026
New version, same problem
coppolaop commentedon Sep 9, 2026
Today, already aware of the ongoing issue with context compaction, I started a completely new chat to implement a new feature.
For the first time, the problem occurred on the very first request. The task was somewhat complex, and during execution Codex automatically attempted to compact the context. As soon as that happened, the request failed with a 404 error and the message shown in the attached screenshot.
This shows that the issue is no longer limited to long-running chats or conversations with a large accumulated context. It can now happen even in a brand-new chat during the first request.
coppolaop commentedon Sep 12, 2026
Since I had received no response on this issue after about two weeks, I decided to install Codex on a second computer, a notebook, and run some tests there. I also reinstalled Codex on my original desktop PC.
I noticed a very unusual difference between the two systems. My desktop has been unable to update Windows, and Codex on that machine also does not offer the newer language models available on the notebook. For example, the version 6 model is available on the notebook but is not available on my desktop.
Unfortunately, despite reinstalling Codex on the desktop, I have stopped using that computer for development for now. I would strongly prefer to work on it, but the recurring issues made it unreliable enough that I moved my development work to the notebook.
I would really appreciate some guidance on whether the Windows version or update status could be related to these problems, and I am still waiting for any feedback on the original issue.
It is very frustrating to have spent roughly two weeks unable to properly use Codex on my main development machine while still incurring the normal costs associated with using the service. I hope someone can take a look at this and provide some direction.
coppolaop commentedon Oct 10, 2026
A final update from my side:
I never received a response to this issue, but I was eventually able to resolve the problem by performing a complete reset of the Codex installation on my desktop.
A normal reinstall was not enough. What worked was removing Codex, deleting the remaining local Codex data/configuration, and reinstalling it from scratch without restoring the previous Codex state.
In my case, this included removing the Codex app package and deleting the local
.codexdata so that the application could rebuild everything from a clean state. I was not able to preserve my previous Codex history through this process, so I committed and saved the work I needed before doing the reset and discarded the old local history.I have now been working with Codex normally for about a month, and the context compaction errors have not returned.
For anyone reaching this issue with the same symptoms, I strongly recommend trying a true clean reinstall rather than simply uninstalling and reinstalling the app. If needed, ChatGPT can also help walk you through identifying the Codex folders and performing the cleanup safely before reinstalling.
This solved the issue for me.