Missing or invalid keys
The backend exits at boot with an error about the signing key or the vault master key.
Symptom
The process exits before serving, with an error that names the signing key or the vault master key, or says a key is too short.
Cause
The environment file is missing, a key was removed, a key is shorter than 32 characters, or the signing key is a well-known example value that the backend rejects on purpose.
Fix
Generate or restore the keys
Run setup, which generates both keys if the environment file is missing and leaves an existing file in place.
npm run setupCheck the length
Both keys must be at least 32 characters. Do not shorten a generated key to fit a form.
Keep the vault key stable
Do not regenerate the vault key on an existing install unless you intend to lose access to existing vault entries.
Restart
Start the stack again and confirm the boot lines no longer report a key error.
Prevention
Back up the vault master key with the manager database. If you must rotate it, retain the previous key so older entries remain decryptable.
Another thing to check
If the error mentions decryption rather than a missing key, the key is present but wrong. Restore the previous master key or set it as the previous key and restart; do not regenerate the vault to get past a decryption error.