Veeam Backup for Microsoft 365 “Failed to find Team mailbox owner account”

The “Failed to find Team mailbox owner account” error can be caused by the owner of the mailbox being moved, or if the owner no longer has a license assigned. Resolving either of these will also resolve your M365 issues. Here are the steps to resolving the cause of either issue:

If the owner was removed from the mailbox:

  • Login to the Teams admin center.
  • Expand Teams, then select to manage teams, and select the Team that is causing the warning.
  • Select the Members tab to either re-add and re-assign the original owner, or select a different member as the owner.

Assigned owner does not have a license:

  • Navigate to your M365 admin center.
  • Open Users, and find the owner of the mailbox.
  • Under the Assign product license tab, assign a valid license.

As these are two of the most common causes of the “Failed to find Team mailbox owner account” error, there may be other issues causing the error.