With the URL set to “https://api.anthropic.com/v1” and a valid Anthropic API key, Test connection fails with “Response status code does not indicate success: 400 (Bad Request)”.
The probable cause is that the request to “/v1/models” omits the required “anthropic-version” header. Reproduced with curl:
- With “x-api-key” and “anthropic-version: 2023-06-01”: success, models listed.
- With “x-api-key” only: 400, “anthropic-version: header is required”.
The provider needs to send “anthropic-version: 2023-06-01” on every Anthropic request.