Repeated 'unknown option --no-warnings' errors in output

[bradygaster]

Problem

During normal Copilot CLI agent sessions, the following error appears repeatedly in the terminal output:

error: unknown option '--no-warnings'

Try 'copilot --help' for more information.
error: unknown option '--no-warnings'

Try 'copilot --help' for more information.
error: unknown option '--no-warnings'

Try 'copilot --help' for more information.
error: unknown option '--no-warnings'

These appear unprompted — the user is not passing --no-warnings directly. Something internal to the CLI or its agent/task spawning infrastructure is passing this flag and it's not being recognized.

Expected Behavior

No error output. If --no-warnings is being passed internally (e.g., to suppress Node.js warnings), it should either:

1. Be passed to the correct target (e.g., NODE_OPTIONS=--no-warnings for Node.js), or
2. Be handled silently if the flag isn't supported

Environment

• OS: Windows 11
• Copilot CLI version: 0.0.407-1
• Occurs during agent task spawning (background mode with task tool)
• Appears multiple times per session, seemingly once per sub-agent spawn

[sebastienros]

Reproduced in 408 on Windows, can share the logs if you ping me on Teams.

(for me: copilot --resume=5730b88b-c6ed-4bfe-8c1c-339afc402fed)

[m3ac-AllbrittenJ]

yep seeing same; very annoying when using sub agents

[jmathes]

reproduced in copilot 1.0.9 on windows 11 by attempting to run copilot from wrapper scripts, without ever entering a copilot CLI session. It's happening before/as the top level CLI launches.

[jolars]

I'm getting this too when running copilot from within neovim.