62594: Acronis Cyber Protect Cloud: Microsoft 365 backup fails with "Cannot back up the primary mailbox of an Microsoft 365 user"

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Applies to: 

Last update: 29-04-2021

Symptoms

Microsoft 365 backup fails.

Error 1
CODE O365MailboxPrimaryMbxBackupError
MESSAGE Cannot back up the primary mailbox of an Microsoft 365 user: 'folder: mailbox primary root: token validation failed'

Error 2
Cannot back up the primary mailbox of an Microsoft 365 user: '[ews-code=ErrorNonExistentMailbox]: The SMTP address has no mailbox associated with it.'

Cause

Error 1: required permissions have been revoked from Acronis Agent in Microsoft 365.

Error 2: the software detects that user has been deleted during discovery activity, which is scheduled once per day. After this deleted user is marked as "grey" and no more backups are executed by schedule for this user. "Grey" user will be deleted from the Cyber Protection console after 7 days in that state.

Solution for error 1

Re-register Microsoft 365 account:

  1. In the Cyber Protection console, navigate to Devices -> All devices.
  2. Click Add.
  3. Select Microsoft 365 for Business.
  4. Confirm granting permissions when prompted.

Solution for error 2

You can force discovery of Microsoft 365 organization by clicking Refresh on Microsoft 365 organization group.