Troubleshooting SharePoint Online backup issues

The following are a few errors that might occur when backing up SharePoint Online sites and related settings. Refer to the troubleshooting guide below to resolve them.

• The remote server returned an error: (400) Bad request.
• The remote server returned an error: (503) Server Unavailable. (or) The remote server returned an error: (429).
• There is not enough space on the disk.
• Microsoft.SharePoint.Client.ServerException: The operation has timed out.
• Enum value 32 is not valid for the type Microsoft.SharePoint.Client.Utilities.PrincipalType and cannot be serialized. Ensure that the necessary enum values are present and are marked with EnumMemberAttribute attribute if the type has DataContractAttribute attribute.
• Additions to this website have been blocked. Please contact the administrator to resolve the problem.
• The MachineKeys folder is increasing in size.
• Duplicate OneDrive for Business sites displayed in the product.
• The attachment could not be downloaded due to retention policy restrictions, inaccessibility during backup, or exclusion based on file type.
• Operation did not complete successfully because the file contains a virus or potentially unwanted software.
• Lifetime validation failed. The token is expired.

The remote server returned an error: (400) Bad request.

Cause:

• This error occurs when a specific list item or file in the site is flagged as malicious by Microsoft. Once flagged, access to that item is restricted via APIs, preventing the backup process from retrieving its data. As a result, the request sent by the backup application is rejected with a 400 Bad Request response.

Resolution:

• Retry the backup to check whether the issue persists.
• The admin should review the affected list or document library to identify any items flagged by the Microsoft security scanner as suspicious or malicious, and remove them if they are not required.
• After addressing the identified items, run the backup operation again.

The remote server returned an error: (503) Server Unavailable. (or) The remote server returned an error: (429).

Cause: This error occurs due to throttling when the number of requests exceeds the limit allowed by the SharePoint Online or OneDrive for Business servers.

Resolution: Retry the backup after some time when the throttling limit resets.

There is not enough space on the disk.

Cause: This error occurs when there is insufficient space on the drive where RecoveryManager Plus is installed.

Resolution: Free up space on the installation drive.

Microsoft.SharePoint.Client.ServerException: The operation has timed out.

Cause: This error occurs when a request to the SharePoint Online or OneDrive for Business endpoint exceeds the allowed execution time, resulting in a timeout.

This can occur due to the following:

• Large data volumes being processed
• High server load on Microsoft services
• Network latency or instability

Resolution:

• Retry the backup, as the issue is often temporary.
• Ensure stable network connectivity between the product server and Microsoft services.
• If the issue still persists, contact support@recoverymanagerplus.com.

Enum value 32 is not valid for the type Microsoft.SharePoint.Client.Utilities.PrincipalType and cannot be serialized. Ensure that the necessary enum values are present and are marked with EnumMemberAttribute attribute if the type has DataContractAttribute attribute.

Cause: The PrincipalType value 32 corresponds to role assignments for external users or groups. These assignments cannot be serialized, per Microsoft.

Resolution:

• Review the role assignments and permission levels for the affected site.
• Update to RecoveryManager Plus build 6312 or any later version of the product, where this issue has been resolved.

Additions to this website have been blocked. Please contact the administrator to resolve the problem.

Cause:

• The site has been deleted or is no longer available within the organization.
• The site is in a locked state (e.g., Read-only or No access), preventing operations such as backup or data access.

Resolution:

• Verify the status of the site in the SharePoint admin center to ensure that the site exists and is accessible.
• If the site is locked, unlock it and retry the backup. Refer to this document to change the site lock state.

The MachineKeys folder is increasing in size.

Cause: This issue occurs when RecoveryManager Plus connects to SharePoint Online with an X.509 certificate, causing the C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys folder size to increase.

Resolution: Open RecoveryManager Plus with elevated Windows permissions and connect to SharePoint Online with the uploaded certificate's thumbprint. If the issue still persists, please contact support@recoverymanagerplus.com.

Duplicate OneDrive for Business sites displayed in the product.

Cause: When a user account is deleted, the OneDrive for Business sites associated with the account are retained and not removed immediately. Recreating the account with the same User Principal Name results in a new site with the same URL suffixed with a number, preventing access to the original site.

Resolution: To resolve this issue, run the Site User Mismatch diagnostic using a SharePoint administrator account. This helps validate and restore ownership and access to the original site. For further details, refer to this page.

The attachment could not be downloaded due to retention policy restrictions, inaccessibility during backup, or exclusion based on file type.

Cause:

• The backup schedule may have failed.
• The file may have been removed due to the retention policies set for the backup schedule.
• The attachment may have been deleted in Microsoft Teams or may not be accessible during the backup.
• The attachment might not be present in the site that has been backed up.
• The file types being downloaded might have been excluded from the backup.
• If the channel is private or shared, the attachment may be stored in its respective site.

Resolution:

• Retry the backup schedule.
• Check the Microsoft Teams site for the attachment.
• If the required file types were excluded, schedule a new backup without selecting those file types in the exclusion list.
• If the channel is private or shared, check the attachments in the respective site.

Operation did not complete successfully because the file contains a virus or potentially unwanted software.

Cause: This error occurs when Windows Defender or another antivirus solution flags a file as malicious or potentially unwanted, preventing the backup from completing. This can happen due to real-time protection blocking access to the file or security policies restricting how flagged files are handled.

Resolution:

• Check the list item's status in the respective site and retry the backup.
• If the issue still persists, contact support@recoverymanagerplus.com.

Lifetime validation failed. The token is expired.

Cause: This error occurs when the access token used for authentication has expired. Access tokens issued by Microsoft have a limited validity period, and once expired, any API request made using that token will be rejected.

Resolution:

• Retry the backup, as a new access token is typically generated automatically.
• Ensure the authentication configuration, including app permissions and credentials, is valid and up to date.
• Verify that the server time is correctly synchronized, as time drift can cause token validation issues.
• If the issue still persists, contact support@recoverymanagerplus.com.