When setting up your Veeam for Microsoft 365 backups, you may select to backup WebParts. If Custom Scripts are not enabled, you will likely run into the warning “Cannot change web part export mode to ‘All’, because custom scripting is disabled for site.” By default, both the “Allow users to run custom script on personal sites” and “Allow users to run custom script on self-service created sites” options are set to “Prevent.” Here are quick steps to get your web parts backing up successfully:
- In the SharePoint admin center, click on “Settings” in the left-hand navigation menu.
- On the Settings page, scroll down to the section titled “Custom Script.”
- If you want to allow custom scripts on personal sites, select the checkbox next to “Allow users to run custom script on personal sites.”
If you want to allow custom scripts on self-service created sites, select the checkbox next to “Allow users to run custom script on self-service created sites.” - After making your desired changes, scroll to the bottom of the page and click on the “OK” button to save the settings.
Additional information can be found here at Veeam and Microsoft.
Source: https://www.managecast.com/veeam-m365-cannot-change-web-part-export-mode-to-all-because-custom-scripting-is-disabled-for-site-warnings/