After changing your password on a remote Fossil repository, you will receive login failures when trying to sync your local repository.
$ fossil sync
Sync with https://blachniet@example.com/test
Round-trips: 1 Artifacts sent: 0 received: 0
Error: login failed
Round-trips: 1 Artifacts sent: 0 received: 0
Sync done, sent: 420 received: 285 ip: 192.168.0.10
$ fossil commit
Autosync: https://blachniet@example.com/test
Round-trips: 1 Artifacts sent: 0 received: 0
Error: login failed
Round-trips: 1 Artifacts sent: 0 received: 0
Pull done, sent: 446 received: 287 ip: 192.168.0.10
Autosync failed.
continue in spite of sync failure (y/N)?
The error occurs because your local repository is still trying to use your old password to sync with the remote.
To update the password in your local repository, run fossil sync <url>. When provided with a URL, this command will prompt you for a password. Enter your new password and instruct Fossil to save it.
$ fossil sync https://blachniet@example.com/test
password for blachniet:
remember password (Y/n)? Y
Round-trips: 1 Artifacts sent: 0 received: 0
Sync done, sent: 456 received: 305 ip: 192.168.0.10
Future syncs will use the new password.