Why do my SSH backups fail after a backup server upgrade.

Applies to: The reported case involved a backup destination upgraded to Statseeker 5.6.2. Do not assume all backup failures have this cause.

If backups fail after the destination is upgraded, check whether its SSH host key has changed.

1. Log in to the Statseeker server initiating the backup as statseeker. Test the destination connection:

   ssh statseeker@<backup-server-IP>Replace the placeholder with the backup server's IP and use the configured destination username if different. Continue below only if the error reports a changed host key or failed host-key verification.

2. Confirm the destination upgrade and its new host key with the backup administrator through a trusted channel. Do not trust a scanned key without independent verification.
3. For the ED25519 case, run this on the initiating server:

   ssh-keyscan -t ed25519 <backup-server-IP>The output includes a line beginning with the destination address and ssh-ed25519.

4. Back up /home/statseeker/.ssh/known_hosts. Using the documented editing procedure, add or replace the verified ED25519 entry for that destination. Preserve unrelated entries; ask Support if unsure which entry to change.
5. Repeat the SSH test, then run the backup test separately. Successful SSH login alone does not prove the backup works.

Keep host-key checking enabled. If errors persist, send Support the SSH error, backup log and both servers' versions.