Challenge
The Backup of SharePoint Sites objects for an Organization added using the Modern App-Only Authentication method displays the warning:
Cannot change WebPart ExportMode to ‘All’. WebPart will be skipped (WebPart ID: <guid>)
Cause
To back up Classic Web Parts using the Modern App-Only Authentication method, Veeam Backup for Microsoft 365 build 8.0.5.20 and earlier required setting the "Export Mode" property of the web part from "None" to "All" to make the Web Part exportable and available for backup. In those earlier versions of Veeam Backup for Microsoft 365, to automatically allow the software to mark a Web Part as exportable, the "Allow custom script" option had to be enabled for affected SharePoint sites. In addition, the “Allow this application to enable export mode for SharePoint Web Parts” option had to be enabled within Veeam Backup for Microsoft 365.
Starting November 1st, 2024, Microsoft removed the ability to keep the "Allow custom scripts" option within SharePoint Online enabled permanently and now automatically disables the option after 24 hours. As a result, those older versions of Veeam Backup for Microsoft 365 will display a warning because they attempt to change the Export Mode.
For more information about the change to the Custom Script setting, see Microsoft Message Center MC714186.
Solution
To resolve this issue, upgrade to Veeam Backup for Microsoft 365 8.1 (build 8.1.0.305) or newer.
More Information
Warning Suppression in Older Versions of Veeam Backup for Microsoft 365
In Veeam Backup for Microsoft 365 build 8.0.5.20 and older, the warning can be suppressed using the information below.
Note: Suppressing the warning will prevent the alert, and WebParts that would have triggered the warning will be skipped silently and not protected by Veeam Backup for Microsoft 365.
Before you begin:
Ensure there are no active Backup or Restore tasks.
Procedure
Perform the following 4 steps on the Veeam Backup for Microsoft 365 server and each of the Proxies:
Stop the Veeam Backup Proxy for Microsoft 365 Service
Edit the Proxy.xml file located here:
