The “Failed to find group owner account” error occurs when a Microsoft 365 group does not have an assigned owner. To fix this error, you can follow these steps:
- Sign into the Microsoft 365 admin center with your admin account.
- Go to the “Groups” section.
- Find the group that is displaying the error and click on it.
- Click on the “Edit” button next to the “Owners” section.
- Assign at least one owner to the group from the list of available users and click “Save”.
If there are no available users in the list, you may need to add a new user to the group or add them to your organization as a user.
Additional information can be found in the Veeam Article KB3105
Source: https://www.managecast.com/veeam-m365-failed-to-find-group-owner-account-error-and-how-to-resolve-it/