Incident Report: SERVER_ROOT_PATH regression broke UI routing
Date: January 22, 2026 Duration: ~4 days (until fix merged January 26, 2026) Severity: High Status: Resolved
Note: This fix is available starting from LiteLLM
v1.81.3.rc.6or higher.
Summary​
A PR (#19467) accidentally removed the root_path=server_root_path parameter from the FastAPI app initialization in proxy_server.py. This caused the proxy to ignore the SERVER_ROOT_PATH environment variable when serving the UI. Users who deploy LiteLLM behind a reverse proxy with a path prefix (e.g., /api/v1 or /llmproxy) found that all UI pages returned 404 Not Found.
- LLM API calls: No impact. API routing was unaffected.
- UI pages: All UI pages returned 404 for deployments using
SERVER_ROOT_PATH. - Swagger/OpenAPI docs: Broken when accessed through the configured root path.

