GitHub Copilot Language model unavailable

[lacaz3tte]

GET /models returns 403 "forbidden: access denied" — Language model unavailable in Copilot Chat

Labels: bug copilot-chat needs-investigation

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Description

Copilot Chat shows "Language model unavailable" in the top-right corner. The extension repeatedly fails to fetch the model list from api.individual.githubcopilot.com/models with HTTP 403. The issue persists across reload, re-authentication, and proxy configuration changes.

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Steps to reproduce

1. Open VS Code with Remote-WSL extension connected to Ubuntu (WSL2)
2. Install GitHub Copilot + GitHub Copilot Chat extensions
3. Sign in to GitHub with an active Individual subscription
4. Open Copilot Chat panel
5. Observe "Language model unavailable" error in top-right corner
6. Check Output → GitHub Copilot Chat for error logs

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Expected behavior

The models list loads successfully and Copilot Chat works normally.

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Actual behavior

Copilot Chat output log shows repeated errors:

2026-05-05 14:56:07.542 [error] Error: Failed to fetch models (f2cd369b-c05e-4348-9e7c-7bc6d91e1ae6): forbidden: access denied
2026-05-05 14:56:08.337 [info]  Fetched model metadata in 792ms
2026-05-05 14:56:08.338 [error] Error: Failed to fetch models (26fa696b-8d4e-48c4-8e5e-debc0be1c826): forbidden: access denied

Manual curl to GET /models with a freshly obtained session token also returns HTTP/2 403:

< HTTP/2 403
< content-type: text/plain; charset=utf-8
<
forbidden: access denied

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Environment

Parameter	Value
OS	Windows 11 + WSL2 Ubuntu 24
VS Code	latest (Remote-WSL)
Subscription	Individual (monthly_subscriber_quota, active)
Network	Corporate network, AS9123
Token endpoint	api.github.com/copilot_internal/v2/token → 200 OK
Models endpoint	api.individual.githubcopilot.com/models → 403

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Workarounds tried (none worked)

• Re-signing in to GitHub
• Setting http.proxy in VS Code settings.json
• Setting / unsetting https_proxy env variable in WSL
• Reloading VS Code window (Developer: Reload Window)
• Deleting ~/.vscode-server/data/User/globalStorage/github.copilot*
• Manual curl with session token + all required headers → same 403

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Additional context

The token endpoint returns 200 OK and a valid session token with correct IP and ASN embedded. However, the subsequent call to /models consistently returns 403. This suggests the issue may be a server-side policy change on the /models endpoint rather than a client-side authentication problem.

Relevant call stack from logs:

at PS._fetchModels (~/.vscode-server/bin/.../extensions/copilot/dist/extension.js:6830:4887)
at async PS.getAllChatModels (~/.vscode-server/bin/.../extensions/copilot/dist/extension.js:6830:2254)
at async $.getAllChatEndpoints (~/.vscode-server/bin/.../extensions/copilot/dist/extension.js:6830:14849)
at async dne._provideLanguageModelChatInfo (~/.vscode-server/bin/.../extensions/copilot/dist/extension.js:1707:4253)