unhandled status from server: 400 Bad Request Request ID: bcc17d96-287a-4587-9bec-8cd1c6befb09

[MojataGroup]

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Copilot Feature Area

Copilot Agent Mode

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I get following error when I am in "Agent" mode in Copilot extension in Xcode and select Claude Sonnet or Claude Sonnet 4.5.

Other Agents work. It is when copilot is trying to read or write files in Xcode. It was working before, but suddenly it stopped.

Sorry, an error occurred while generating a response.
Details: unhandled status from server: 400 Bad Request Request ID: bcc17d96-287a-4587-9bec-8cd1c6befb09

Please help.

[DavitEgoian]

1. Update the Copilot for Xcode Extension

   • Support for newer models like Claude Sonnet 4.5 is often added in the very latest versions of the extension.
   • Check for updates in the Mac App Store or via the extension's update mechanism (depending on how you installed it) to ensure you are on the latest release.

2. Re-authenticate (Sign Out and Back In)

   • The 400 error can sometimes happen if your current authentication token doesn't have the updated permissions required for the new models.
   • Sign out of your GitHub account within the Copilot extension in Xcode.
   • Sign back in to refresh your token.

3. Check Organization Policy (Business/Enterprise Users)

   • If you are using Copilot through a Business or Enterprise plan, an organization administrator must explicitly enable the Claude Sonnet models in the organization's Copilot settings.
   • Even if the model appears in the dropdown, the server will reject the request (causing a 400 error) if the policy hasn't been enabled for your organization.

4. Switch to "Auto" or "GPT-4o" Temporarily

   • If the issue persists, select the Auto model or revert to the standard GPT-4o model to continue working. The "Auto" setting attempts to pick the best available model and may bypass specific model availability issues.

If none of the above fixes the issue, you can report it on the Copilot for Xcode GitHub repository or contact GitHub Support directly, as it may be a temporary service-side bug affecting your specific account setup.

[MojataGroup]

Hi,pre-release version 0.46.159 solved the error related to error 400.ThankOn Jan 9, 2026, at 3:43 PM, Davit Egoian ***@***.***> wrote: Update the Copilot for Xcode Extension Support for newer models like Claude Sonnet 4.5 is often added in the very latest versions of the extension. Check for updates in the Mac App Store or via the extension's update mechanism (depending on how you installed it) to ensure you are on the latest release. Re-authenticate (Sign Out and Back In) The 400 error can sometimes happen if your current authentication token doesn't have the updated permissions required for the new models. Sign out of your GitHub account within the Copilot extension in Xcode. Sign back in to refresh your token. Check Organization Policy (Business/Enterprise Users) If you are using Copilot through a Business or Enterprise plan, an organization administrator must explicitly enable the Claude Sonnet models in the organization's Copilot settings. Even if the model appears in the dropdown, the server will reject the request (causing a 400 error) if the policy hasn't been enabled for your organization. Switch to "Auto" or "GPT-4o" Temporarily If the issue persists, select the Auto model or revert to the standard GPT-4o model to continue working. The "Auto" setting attempts to pick the best available model and may bypass specific model availability issues. If none of the above fixes the issue, you can report it on the Copilot for Xcode GitHub repository or contact GitHub Support directly, as it may be a temporary service-side bug affecting your specific account setup. —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***>

[Arefin994]

Hi @MojataGroup,

This doesn’t look like anything you did wrong.

Since it:

• only happens in Agent mode
• only affects Claude Sonnet / Sonnet 4.5
• shows up when Copilot tries to read or write files
• and other agents still work

…it’s very likely a server-side Copilot bug or a recent regression with the Claude agents. The 400 Bad Request plus the Request ID usually means the request is being rejected on GitHub’s backend, not in Xcode.

Things worth trying

• Fully restart Xcode and re-sign into GitHub
• Make sure the Copilot extension and Xcode are up to date
• Use a non-Claude agent as a temporary workaround

What to report

When GitHub staff look at this, the important part is the Request ID:
bcc17d96-287a-4587-9bec-8cd1c6befb09

Mention that it used to work and stopped suddenly, and that it only breaks for Claude agents during file operations.

Hopefully they can trace it quickly using that ID.