Known errors, warnings, workarounds and fixes for Microsoft SharePoint backups with M365 backup powered by Veeam 



Here is a list of known workarounds and fixes for warnings and errors you may get in your backup reports for Microsoft SharePoint.

Warning : Cannot change web part export mode to ‘All’, because custom scripting is disabled for site: https://xxxxxxxxxxxxxxxx Web part will be skipped

Cause :

To back up Web Parts, M365 backup powered by Veeam requires to set the "Export Mode" property of the web part from "None" to "All" to make this Web Part exportable and available for backup.

Solution :

You must enable the "Allow custom script" option for the affected SharePoint sites.

Warning : Processing site xxxxxxxxxxxxx finished with warning: Failed to backup item: xxxxxxxxxxxxxx, Item may have a virus reported by the virus scanner plug-in

Cause :

Items being backed-up may be blocked by the internal SharePoint Online antivirus. For more information, see this Microsoft article.

Solution :

To validate if any items are infected, open the Site that cannot be backed up and try downloading files manually. Files considered malicious are blocked from downloading. If so, you probably can safely delete the infected blocked files. For more information, see this Microsoft article.

Warning : Failed to resolve sites: Cannot contact site at the specified URL XXXXXXXXXXXXXXXXXXXXXX. Access to this Web site has been blocked. Please contact the administrator to resolve this problem.

Cause :

The lock status for the site is configured to disallow access.

Solution :

Please follow this Microsoft article to change the lock state for a site :

Error: The identity of the calling application could not be established.

Cause :

The enterprise application named "M365 backup powered by Veeam" was deleted in Azure AD. Backup jobs cannot run without this application.

Solution :

Please contact our support team. We will have to proceed with the Microsoft tenant setup again in the backend using a user with the Global Administrator role.


Warning: Failed to resolve personal site owner. The user may not have a valid Microsoft 365 license with a SharePoint plan enabled.

Cause :

When a M365 user is deleted, the M365 license is unassigned and data is kept for thirty (30) days. As the personal site still exists, when the backup is performed, it returns a warning because the user was removed as the site owner.

Solution :

1- Wait for thirty (30) days to get the user and data completely deleted.

2- Over thirty (30) days, the site may become an ophaned site. To remove the orphaned site, please do the following :

  • Launch Windows PowerShell (Run as Administrator)

  • Run this command: Get-Module -Name Microsoft.Online.SharePoint.PowerShell -ListAvailable | Select Name,Version

  • Run this command: Install-Module -Name Microsoft.Online.SharePoint.PowerShell

  • Enter "Y" or "A"

  • Run this command: Connect-SPOService -Url
    (Replace "tenantname" with the name of your "" tenant name)
  • Authenticate with an account that has the Global Administrator role

  • Run this command: Remove-SPOSite -Identity -NoWait
    (Replace "tenantname" with the name of your "" tenant name. Replace "sitename" with the directory in which you are experiencing warnings).

Error: Failed to process team: [XXXXXXXXXXXXX]. Failed to find Team mailbox owner account.

Cause :

Impersonation is not possible if a team does not have a least one (1) owner. If no owner is assigned to the team, the team is considered as an orphaned team.

Solution :

Please make sure to assign an owner to each of the teams in Microsoft Teams. Please follow this Microsoft article for more information on assigning owners to teams in Microsoft Teams.