Codex Desktop context compaction fails with /responses/compact 404 on Windows
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- Dominant language
- Rust
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Description
What version of the Codex App are you using (From “About Codex” dialog)?
26.506.3741.0
What subscription do you have?
ChatGPT Plus
What platform is your computer?
No response
What issue are you seeing?
Codex Desktop works normally until the conversation reaches the automatic context compaction threshold.
When context compaction is triggered, the UI displays:
“Context automatically compacted”
Immediately afterwards, Codex returns:
Error running remote compact task: unexpected status 404 Not Found
url: https://chatgpt.com/backend-api/codex/responses/compact
After this happens, the conversation cannot continue normally. Sending another message causes the same remote compact 404 error again.
I have reproduced this issue in multiple newly-created Codex Desktop conversations.
Environment:
- Windows 11 x64
- ChatGPT Plus
- Codex Desktop: latest available version
- Model: GPT-5.5
- Reasoning level tested: High / Extra High
- Codex CLI installed separately: 0.147.0
The problem occurs specifically when automatic context compaction is triggered.
What steps can reproduce the bug?
- Open Codex Desktop on Windows.
- Start a new conversation using GPT-5.5.
- Work normally in the conversation and let the context grow.
- Continue until Codex automatically triggers context compaction.
- The UI displays “Context automatically compacted”.
- The request to /backend-api/codex/responses/compact returns HTTP 404.
- Send another message in the same conversation.
- Codex attempts context compaction again and returns the same 404 error.
This has been reproduced in multiple newly-created conversations, not just one old or unusually long thread.
What is the expected behavior?
No response
Additional information
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the failure on Windows and trace the request to /backend-api/codex/responses/compact. Check how automatic compaction handles the 404, then verify that compaction succeeds and a follow-up message can continue the conversation without repeating the error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- api, desktop
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Active
- Clarity
- Clearly specified
- Newbie friendliness
- 42/100