codex - 💡(How to fix) Fix Rider Codex - windows defender - trojan Trojan:Script/Wacatac.F!ml [1 participants]

"Failed to initialize ACP session. Error: Codex process has exited with code 1"

TL;DR

The issue is likely due to Windows Defender falsely flagging the codex-x86_64-pc-windows-msvc.exe file as a Trojan, causing the Codex process to exit with code 1.

Guidance

• Verify that the codex-x86_64-pc-windows-msvc.exe file is not actually malicious by checking its digital signature and verifying it with the JetBrains team.
• Try adding an exclusion to Windows Defender for the AppData\Local\JetBrains\Rider2026.1\aia\codex\bin directory to prevent it from scanning the file.
• Check if there are any updates available for the Codex plugin or Rider IDE that may resolve the issue.
• Consider submitting a false positive report to Microsoft for the Trojan:Script/Wacatac.F!ml detection.

Example

No code snippet is provided as this issue is related to a false positive detection by Windows Defender.

Notes

The issue may be specific to the user's environment or Windows Defender configuration. The provided steps to reproduce the bug may not work for everyone.

Recommendation

Apply workaround: Add an exclusion to Windows Defender for the AppData\Local\JetBrains\Rider2026.1\aia\codex\bin directory, as this is a more immediate solution to the problem.