Codex Pro GPT-5.4 long context regressed: ~672k worked Apr 22, ~290k fails Apr 23

Open 💬 8 comments Opened Apr 23, 2026 by markobogoevski-dev

💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

Codex desktop app: 26.417.41555
Bundled app-server: codex-cli 0.122.0-alpha.13
Homebrew CLI after upgrade: codex-cli 0.123.0
Auth mode: ChatGPT
Plan shown in logs: pro
Rate limit shown in logs: limit_reached=false

Config:
model = "gpt-5.4"
model_context_window = 1000000
model_auto_compact_token_limit = 700000

Observed:

Apr 22: GPT-5.4 turns succeeded around 635k-672k total tokens with auto_compact_limit=700000.
Apr 23: GPT-5.4 turns started failing around 270k-309k tokens with:

"Codex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying."

Expected:
Codex Pro + GPT-5.4 should continue using the long-context route as it did Apr 22, or auto-compact before rejection.

Actual:
Client keeps auto_compact_limit=700000, but backend/app-server rejects around the ~272k boundary.

View original on GitHub ↗

8 Comments

github-actions[bot] contributor · 2 months ago

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

#19116
#18052
#18136
#18827

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hookenful · 2 months ago

@markobogoevski-dev you have paid plan or have pending due payment?

markobogoevski-dev · 2 months ago

@markobogoevski-dev you have paid plan or have pending due payment?

I have a paid plan, email is markobogoevski@gmail.com.

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JanDuchscherer104 · 2 months ago

Same issue here.

Issue in both Codex CLI and Codex Windows App (project inside WSL)
GPT5.4 xhigh was at 221k / 950k, then I started plan mode. And it crashed due to

Codex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying.

Between it being at 221k tokens and the crash, it read 7 files and did 3 rg searches. Another codex instance investigated these actions from the Codex Sessions jsonl and estimated a token usage between 35k and 50k token.
I had this issue multiple times today and every time it happened in plan mode or right after confirming a suggested plan.

config.toml

model = "gpt-5.4"
model_context_window = 1050000
model_auto_compact_token_limit = 800000

MOON-DREAM-STARS · 2 months ago

me too, I also meet this question, since updated the newest Codex app

hookenful · 2 months ago

@etraut-openai

daothinh · 2 months ago

Same ! I also ran into the same issue as you when using codex-cli version 0.123

MOON-DREAM-STARS · 2 months ago

I may know why now. It's probably because yesterday the request rate for GPT 5.4 was routed to GPT 5.5 again. Since the maximum context window size for GPT 5.5 is only 256k, it truncates requests at this point each time.