[Windows Desktop 26.818.8289.0] Feedback upload failed because Codex runtime crashed with 0xC000001D

What version of the Codex App are you using (From “About Codex” dialog)?

26.818.8289.0

What subscription do you have?

No ChatGPT subscription. I am using an API key with a custom OpenAI-compatible provider.

What platform is your computer?

Windows 11 x64

What issue are you seeing?

Problem

The built-in feedback submission in Codex fails with the message:

Feedback upload failed

The dialog says:

The upload failed, but your Feedback ID is unchanged.

Feedback ID:

01a03c7a-7507-7e62-85b0-eefd9cb579dc

Root cause found in the local logs

When submitting feedback, Codex runs a feedback doctor report before uploading the feedback. The diagnostic process crashes with:

doctor report for feedback did not produce JSON; skipping attachment

Executable:

C:\Users\27471\AppData\Local\OpenAI\Codex\bin\d5f4c71927a04589\codex.exe

Exit code:

0xc000001d

This is Windows STATUS_ILLEGAL_INSTRUCTION.

After that, the feedback upload fails with:

Codex app-server is not available

The local log also records:

Failed to submit feedback

The same STATUS_ILLEGAL_INSTRUCTION crash happens when sending a normal message in a new conversation.

Environment

• Codex Desktop version: 26.818.8289.0
• Bundled app-server version before the feedback attempt: 0.149.0-alpha.4.3
• Windows 11 x64
• Custom OpenAI-compatible provider
• Model: gpt-5.5
• Wire API: Responses API
• Provider base URL: https://ai.aifiys.com/v1

Important observations

The feedback upload failure appears to be caused by a local native Codex runtime crash, not by the feedback text or an HTTP API error.

The Feedback ID remained unchanged, but the local logs indicate that the feedback upload did not complete.

What steps can reproduce the bug?

1. Start Codex Desktop on Windows 11 x64.
2. Use a custom OpenAI-compatible provider configured with the Responses API.
3. Open a conversation or create a new conversation.
4. Type /feedback in the composer.
5. Fill in the feedback form and submit it.
6. Observe the "Feedback upload failed" dialog.

The issue can also be reproduced by sending a normal text message. The bundled Codex runtime exits with 0xc000001d after the request starts.

What is the expected behavior?

The feedback should be uploaded successfully and Codex should display a confirmation that the feedback was received.

Additional information

A clean reinstall of the Codex App was already performed. The user's .codex directory, authentication data, configuration, sessions, and logs were preserved.

Windows Error Reporting also recorded repeated crashes for Codex with the same native crash bucket:

b5807389cbd75b9cd7669a843aaa2119

The built-in feedback upload itself cannot complete because the local diagnostic helper crashes before the upload request finishes.

Start by reproducing the crash in the Windows Codex Desktop runtime using a custom OpenAI-compatible provider, then inspect the bundled codex.exe and the local logs around the feedback doctor and app-server. Use the reported 0xc000001d exit code and crash bucket to narrow the native failure. Done means normal messages and feedback submission no longer cause the runtime to exit, and feedback completes successfully.