# AUTHN

4 codes.

| Code | What happened | Why | What to do | Retryable |
| --- | --- | --- | --- | --- |
| `AUTHN/REQUIRED` | Sign in to do this. | This action is available to signed-in people only. | Sign in, then try again. | no |
| `AUTHN/SESSION_EXPIRED` | Your session has ended. | Sessions end after a period of inactivity or a fixed lifetime, to protect the account. | Sign in again to continue. | no |
| `AUTHN/LOGIN_FAILED` | The sign-in was not accepted. | The email or password does not match what is on file; which one is never said, to protect the account. | Check both and try again, or reset the password. If a new password was issued recently, use the newest one. | no |
| `AUTHN/DEVICE_SESSION_INVALID` | This device is no longer signed in or registered. | The device credential this browser presented is no longer valid — it was unpaired, replaced, or expired. | Pair or sign the device in again. | no |