This article explains backup warnings.
When a Datto appliance attempts a backup, it tries three times before it errors out:
- If the first backup attempt fails, it writes a warning to the backup log and tries again.
- If the second backup attempt is successful, the backup completes, but you will get a backup warning. If the second backup attempt fails, it tries a third time.
- If the third attempt is successful, you will get a backup warning that tells you that a previous attempt failed. If the third attempt fails, you will see a backup error, rather than a warning.
The purpose of the warnings is to let you know that there was a transient issue that prevented a backup attempt, but that the backup eventually succeeded. How you proceed depends on the type of warning and how many of them you get.
If you get many backup warnings, attempt to troubleshoot the problem as if you had gotten a backup error. See the article Start Here To Troubleshoot A Windows Backup Error Or Warning.