Models visible in VS Code Copilot picker but return "model_not_supported" (400) when used

[hbgangcn1]

🏷️ Discussion Type

Question

💬 Feature/Topic Area

VS Code

Body

Description
Several models appear in the VS Code Copilot Chat model picker dropdown, but selecting and using any of them results in a 400 error:
{"error":{"message":"The requested model is not supported.","code":"model_not_supported","param":"model","type":"invalid_request_error"}}
This happens both in VS Code's native Copilot Chat and via third-party tools using the GitHub Copilot API.
Affected models:

• Claude Haiku 4.5
• Gemini 3 Flash (Preview)
• GPT-5 mini
• GPT-5 nano
• Grok Code Fast 1
  Models that work without issues:
• Claude Opus 4.6 ✅
• Claude Sonnet 4.6 ✅
• GPT-5.4 ✅
• Gemini 3.1 Pro Preview ✅
  Steps to reproduce:

1. Open VS Code with the latest GitHub Copilot extension
2. Open Copilot Chat (Ctrl+Shift+I or via sidebar)
3. Click the model picker dropdown at the top of the chat panel
4. Select any of the affected models (e.g. "Claude Haiku 4.5")
5. Send any message
6. Error: "Sorry, your request failed."
   Error details (Claude Haiku 4.5 example):

• Copilot Request ID: 9616bbe0-8f5b-41e6-a7ce-7bb962b101a5
• GH Request ID: B63A:80FC5:13E8498:1592B96:69E0BF9F
• Response: 400 model_not_supported
  Environment:
• VS Code: latest stable
• GitHub Copilot extension: latest
• OS: Windows 11
• Subscription: GitHub Copilot (active)
  Questions for the community:

1. Is anyone else seeing this? Are these models working for you?
2. Are these models region-restricted, or do they require a specific subscription tier (Pro/Business/Enterprise)?
3. Is there a setting I'm missing, or are these models simply not yet available despite showing up in the picker?
   Any insight would be appreciated. Thanks!

[xuyushun441-sys]

i have enterprise plan and models are enabled, in github.com i can use opus model in copilot agent, but i select claude agent, it returns model_not_supported .
but in vscode, i can use copilot agent and claude agent

[hbgangcn1]

This is not an issue because it happened during Github Copilot maintenance.

[xuyushun441-sys]

no, i have this error for 3 days