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Random compaction bug blocking session completely. #38240
Description
What version of Codex CLI is running?
codex-cli 0.128.0
What subscription do you have?
Pro
Which model were you using?
gpt-5.5 medium
What platform is your computer?
CachyOS
What terminal emulator and version are you using (if applicable)?
bash - Konsole
Codex doctor report
■ Error running remote compact task: unexpected status 404 Not Found: {"detail":"Not Found"}, url: https://chatgpt.com/backend-api/codex/responses/compact, cf-ray: a2a1db60588c37cd-BKK, request id: 6a8baa3a-
11cd-45f7-a784-86a9de43e263
[tkb@TANELORN-CACHYOS SideraV7]$ codex doctor --json
error: unexpected argument '--json' found
tip: to pass '--json' as a value, use '-- --json'
Usage: codex [OPTIONS] [PROMPT]
codex [OPTIONS] <COMMAND> [ARGS]
For more information, try '--help'.
[tkb@TANELORN-CACHYOS SideraV7]$What issue are you seeing?
During compaction hit a status 404 error in codex.
What steps can reproduce the bug?
Uploaded thread: 019fe013-cc73-7780-a17f-7cc61998d68e
What is the expected behavior?
No error, keep working.
Additional information
No response
Activity
Sorbe1 commentedon Aug 12, 2026
Token usage: total=24,177,136 input=20,178,048 (+ 965,125,760 cached) output=3,999,088 (reasoning 200,611)
Sorbe1 commentedon Aug 12, 2026
/status
╭────────────────────────────────────────────────────────────────────────────────────────────────╮
│ >_ OpenAI Codex (v0.128.0) │
│ │
│ Visit https://chatgpt.com/codex/settings/usage for up-to-date │
│ information on rate limits and credits │
│ │
│ Model: gpt-5.5 (reasoning medium, summaries auto) │
│ Directory: /data/bulk/SideraV7 │
│ Permissions: Custom (danger-full-access, on-request) │
│ Agents.md: AGENTS.md │
│ Account: xxxxx@gmail.com (Pro) │
│ Collaboration mode: Default │
│ Session: 019fe013-cc73-7780-a17f-7cc61998d68e │
│ │
│ Context window: 8% left (239K used / 258K) │
│ Weekly limit: [██████████████░░░░░░] 69% left (resets 10:52 on 18 Aug) │
│ GPT-5.3-Codex-Spark Weekly limit: [████████████████████] 100% left (resets 02:36 on 20 Aug) │
╰────────────────────────────────────────────────────────────────────────────────────────────────╯
Sorbe1 commentedon Aug 13, 2026
Still reproducible after 10+ hours across two separate Codex sessions. Public OpenAI status reports fully operational and contains no corresponding incident. Requests consistently return HTTP 404 from /backend-api/codex/responses/compact.
Sorbe1 commentedon Aug 13, 2026
Impact: Pro Level Customer Development with Codex now impossible. Customer operations completely BLOCKED.
This is now a Pri 1, Sev 1 class full work stoppage incident.
SunMaple11 commentedon Aug 13, 2026
The same error is appeared on my 0.147 codex cli
■ Error running remote compact task: unexpected status 404 Not Found: {"detail":"Not Found"}, url:
https://chatgpt.com/backend-api/codex/responses/compact, cf-ray: a2a63697bb8ea0de-NRT, request id:
39b24f5b-0bb3-4535-a643-d14319dcce5f
If I open a new session, when the context neally full, the error will be shown too.
The codex say this is the problem of openai backend. Hope it can be solved quickly.
Sorbe1 commentedon Aug 13, 2026
■ Error running remote compact task: unexpected status 404 Not Found: {"detail":"Not Found"}, url: https://chatgpt.com/backend-api/codex/responses/compact, cf-ray: a2a7ff321d25692e-BKK, request id: ef69eb19-23
26-40fc-86a1-2e4da2bf0923
SunMaple11 commentedon Aug 13, 2026
same problem. I asked codex in a new session and he told me it is caused by the backend server of openai.
SunMaple11 commentedon Aug 14, 2026
I have solved this problem.
■ Error running remote compact task: unexpected status 404 Not Found: {"detail":"Not Found"}, url:
https://chatgpt.com/backend-api/codex/responses/compact, cf-ray: a2a63697bb8ea0de-NRT, request id:
39b24f5b-0bb3-4535-a643-d14319dcce5f
This is my error
It's 2 reasons I've known to cause it:
1 codex version too old.
2 some wrong configurations. This is my problem. Open ~/.codex/config.toml and search any wrong configurations.
Because the remote compaction always error in the past so I add this config in my config.toml
[feature]
remote_compaction_v2 = false
local_thread_store_compression = true
It's wrong config. So I delete this three lines and continue my error session. It is work.
Hope to help you. @Sorbe1
jdcodes1 commentedon Aug 18, 2026
Root-caused this in #38323 (same
unexpected status 404from/backend-api/codex/responses/compact): when remote compaction fails, codex's only recovery is retrying the same remote endpoint with a fallback model (core/src/compact_model_fallback.rs#L9-L20), so a route-level 404 fails both attempts and the turn errors out. Because compaction fired due to a full context, every continuation re-triggers it — that's why the session blocks completely instead of recovering. The clean fix is falling back to the existing local compaction path (run_compact_task) when the remote endpoint 404s; details in the linked comment.Sorbe1 commentedon Aug 22, 2026
_> [feature]
This addition to ~/.codex/config.toml provided a temporary work around until the backend issue is fixed. Credit to SunMaple11
I also upgraded to gpt-5.6-sol (reasoning high) to supposedly improve my context size.