When backing up your Office 365 products you’ll need to consider what type of authentication will best suit your needs.
The different methods are Modern Application-only and Modern with Legacy authentication.
The main reason as to why you need to choose between the two is due to what kind of security settings you have within your Azure tenancy.
If you use Conditional Access policies then you’ll need to use Modern with Legacy authentication but if you use Security Defaults, then you can use either.
However, both authentication methods come with their own set of drawbacks/limitations, when it comes to backing up and restoring.
Modern application-only authentication has the following limitations:
Backup
- Discovery Search and Public Folder mailboxes are not supported.
- Dynamic Distribution groups are not supported.
- The type property for shared and resource/equipment mailboxes cannot be resolved. Such mailboxes will be available for backup with a general ‘User’ type.
- SharePoint Web Parts can only be backed up if their ‘exportmode’ property is enabled. Nonexportable Web Parts are not supported.
Restore
- OneNote restore is not supported.
- SharePoint Web Part customized template cannot be preserved upon a restore. All Web Parts will be restored with the default template.
- The ‘Allow multiple responses’ setting in survey lists within team modern sites is not preserved upon a restore.
Modern authentication method with legacy protocols has the following limitations in backup and restore functionality:
- Team backup required the VBO user to have a Team license.
