## The symptom

Vault v0.9.5 hangs on shutdown. The server stops responding during shutdown and
never exits. A token with a negative TTL is never cleaned up, the token
hierarchy keeps growing, and revocation appears stuck.

## Why

This was a Vault deadlock in the shutdown path, fixed in 0.9.6 with new
revocation mechanics.

## The fix

Upgrade to Vault 0.9.6 or later. After upgrading, the revocation loop no longer
blocks shutdown. The reporter confirmed the fix resolved it.

## Workaround for already-stuck instances

Run the tidy operation on tokens to clean up expired tokens that were never
removed:

```
vault operator tidy
```

Do this before or as part of the upgrade for instances that are already wedged.