Backup fails with this error message: -
Backup failed – the backup wrapper failed to write a valid log file
The "agent credential" user on the agent machine does not have sufficient permissions to run a backup.
1) go to Agent > Set Credential page to check which user backups will run as
2) ensure it belongs to local "administrators" group on the backup agent (it may be a domain account, but must belong to local group)
Kaseya VSA (Backup module) - all versions