The 't0p-s3cr3t' default was dead code on every supported startup path:
start.sh, start_windows.bat and `open-webui serve` all set or
auto-generate WEBUI_SECRET_KEY before the backend imports env.py. It was
only ever reachable by invoking uvicorn directly, which is unsupported
and unsafe (the app would then sign tokens/cookies with a public,
hardcoded key). It also keeps getting reported as a vulnerability because
it looks dangerous, even though it is unreachable in practice.
Drop the fallback (default to '') so an unset key is caught by the
existing WEBUI_AUTH guard, and replace the vague error with a clear,
actionable message explaining that the key is a hard requirement and how
the supported start methods provide it. Exit cleanly via SystemExit
instead of raising a ValueError traceback.
WEBUI_AUTH=False keeps working unchanged (key defaults to '').
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
