What this error means
LiteLLM Vertex AI: wrong base URL for us/eu multi-region endpoints is a LiteLLM failure pattern reported for developers trying to fix litellm wrong vertex ai url construction for us/eu multi-region endpoints. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
Google introduced multi-region endpoints (us, eu) on April 16, 2026. LiteLLM's get_vertex_base_url() constructs wrong URLs. Generated URLs don't exist and return HTML error pages. Fix: use aiplatform.{region}.rep.googleapis.com format.
Common causes
- LiteLLM generates wrong URLs (us-aiplatform.googleapis.com instead of aiplatform.us.rep.googleapis.com) for new Vertex AI multi-region endpoints
- Google introduced multi-region endpoints (us, eu) on April 16, 2026. LiteLLM's get_vertex_base_url() constructs wrong URLs. Generated URLs don't exist and return HTML error pages. Fix: use aiplatform.{region}.rep.googleapis.com format.
Quick fixes
- Confirm the exact error signature matches
LiteLLM Vertex AI: wrong base URL for us/eu multi-region endpoints. - Check the LiteLLM account, local tool state, and provider configuration involved in the failing workflow.
- Compare the failing environment with a known working setup, then change one configuration value at a time.
Platform/tool-specific checks
- Verify the command, editor, extension, or API client that produced the error.
- Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
- Avoid deleting credentials, local model data, or project settings until the failing scope is clear.
Step-by-step troubleshooting
- Capture the exact error message and the command, editor action, or request that triggered it.
- Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
- Review the source evidence below and compare it with your environment.
- Apply one change at a time and rerun the smallest failing action.
- Keep the working fix documented for the team or deployment environment.
How to prevent it
- Keep provider/tool configuration documented.
- Record non-secret diagnostics such as tool version, provider name, model name, and command path.
- Add a lightweight check before CI or production workflows depend on the tool.