You fixed the endpoint.
You rewrote the dependency.
You regenerated the token.
Still 401.
Here’s the uncomfortable truth:
401 is not the root cause.
It’s the signal that something deeper is inconsistent.
In FastAPI authentication flows, 401 usually appears when:
The SECRET_KEY used to sign the token is not the one used to verify it
Docker injects a different .env than your local environment
Multiple instances are running with inconsistent configurations
The token algorithm (HS256 / RS256) does not match
Clock drift invalidates the token timestamp
The controller is fine.
The route is fine.
The dependency is fine.
The layers are not aligned.
Authentication is not just code.
It’s configuration.
It’s environment.
It’s deployment consistency.
When /token works but /me returns 401,
your application is telling you:
“The layers don’t agree.”
Stop fixing the endpoint.
Start mapping the layers:
Environment variables
Key consistency
Container configuration
Token structure
Deployment topology
401 is not your enemy.
It’s the signal that your architecture is out of sync.
Treat it as a bug, and you’ll chase symptoms.
Treat it as a signal, and you’ll repair the architecture.
I built a reproducible playground for this type of incident:
https://github.com/hiro-kuroe/fastapi-auth-crud-docker
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