Alert: Microsoft 365 site backup task failure with error"Access Denied"


M365 Mailbox backup task fails, and this Alert is generated:

Desc: o365 HTTP call errored with response StatusCode: 403,"accessDenied"

Root Cause

Below are some of the common causes for this failure.

  • The Sharepoint site was created internally by Microsoft Loop. Clumio cannot back up Sharepoint data created through MS Loop. These sites are internally created by Microsoft for content storage purposes.
  • Clumio app on Azure no longer has the required permissions.

For more information on Microsoft Loop, see the article


  • Remove the backup policy and unprotect sites created by Microsoft Loop on the Clumio Portal.
  • Verify that the Clumio app is still in your Azure portal with the correct permissions. And, verify the user account Clumio uses for authentication. To verify these issues on Azure, go to  Azure portal > Enterprise Applications, and find the Clumio app.

Note: The Mailbox backup tasks will continue to fail until you resolve this issue.

Contact [email protected] with any questions or concerns.