[Updated] – Veeam Backup for Office 365 Update 4c

Yesterday the product team has released a new update for Veeam Backup for Office 365. The update 4c introduce these new features:

  • Support for Office 365 tenants using modern app-only authentication with disabled legacy protocols. In the new mode, VBO performs all its backup and restore operations using an Azure AD application instead of user credentials. This new mode addresses the needs of customers using Microsoft Security Defaults in their Office 365 tenant organizations.
  • Support for leveraging auxiliary backup applications to enable faster SharePoint Online and OneDrive for Business backups for Office 365 tenants using modern app-only authentication.
  • The built-in product auto-upgrade feature now automatically installs the new and missing Veeam Explorers that come as part of Veeam Backup for Microsoft Office 365 package, as well as the newest patches for Veeam Backup for Microsoft Office 365.
  • Enhanced UI for Backup Accounts Manager allowing for easier selection of a security group and managing dozens of accounts.

The following is a list of issues resolved in Veeam Backup for Microsoft Office 365 4b:

  • After an upgrade from Veeam Backup for Microsoft Office 365 version 4a to version 4b synchronization between the Proxy and Archiver services fails because of object storage repository status check.
  • Applying retention policy fails with the “JetError -1605, JET_errKeyDuplicate, Illegal duplicate key”.
  • After a username has been changed in Office 365, a new username is not reflected in the output of the “Get-VBOLicensedUser” PowerShell cmdlet and the built-in License Overview report.
  • After existing backup data migration to an object storage repository, old restore points are missing some of the SharePoint data.
  • Deleting an organization with configured auxiliary backup accounts from the Veeam Backup for Microsoft Office 365 scope fails with the “Organization with the same name already exists” or “JetError -1809, JET_errPermissionDenied” error.
  • Backup data migration from a local backup repository to an Azure Blob storage repository completes with the “Failed to move all objects” warning.
  • Under certain conditions, executing the “Disable-VBOJob” PowerShell cmdlet hangs.
  • Cohesity S3 object storage cannot be added as an object storage repository.


  • When downloading attachments during a SharePoint Online site backup, backup job fails with the “Failed to backup list: File not found in the database” error.
  • Backup of an OneDrive account fails with the “Item has been changed during backup” error.
  • Under certain conditions, backup of an archive mailbox in a hybrid organization setup fails with the “ErrorInvalidUserPrincipalName” error.


  • In the BaaS setup, a SharePoint site list explore from a tenant side fails with the “Object synchronization method was called from an unsynchronized block of code” error.
  • Under certain conditions, files are skipped during SharePoint Online restore to the original location.
  • Under certain conditions, folders cannot be created during SharePoint Online restore to the original location.
  • During SharePoint Online restore using REST API, the “GET Libraries” request fails with the “Invalid root web permissions” error.
  • OneNote items export fails with the “Failed to create cab file” error.
  • SharePoint Online document restore fails with the “A file or folder with the name already exists” and “User ID login not found on SharePoint server” errors if a folder containing this document has been moved to another location.
  • OneDrive export completes with the “No items were saved” message.
  • An attempt to start a restore session via REST API fails after numerous attempts to get the new access token for a specific user account.
  • Under certain conditions, exporting of an Exchange item to a PST or MSG fails with the “Value cannot be null” error.

Cumulative Update 4c KB3222

A cumulative update has been released to fix some issues and improve the product.


  • Optimized reading from object storage repository to reduce the cost of querying the first 100 items in a folder when exploring backups with Veeam Explorers.
  • Parallel processing of requests for obtaining used space in backup repositories initiated via PowerShell or REST API on multiple proxies.
  • Reduced backup times to object storage repositories targets when processing SharePoint and OneDrive for Business items with thousands of versions.

Issue Solved

  • After updating to Veeam Backup for Microsoft Office 365 4c (build backups start to fail with the “Proxy offline time exceeded” error. For more details, see KB3216.
  • Under certain conditions, the backup proxy server sends ‘Success’ notifications about backup job completion results for backup jobs failed with the “Proxy offline time exceeded” error.
  • Unable to update certificate information for S3 Compatible object storage after the trusted certificate has been changed and a backup repository extended to such object storage goes to the ‘Invalid’ state.
  • OneDrive restore in the Modern Authentication mode fails with the “Cannot connect to Office 365” error.
  • Backup job initiated with the /v4/Jobs/{backup_job_id}/action REST API request performs full backup sync instead of incremental sync.
  • In the UI, changes to the schedule of applying retention policy settings for existing backup repositories are not saved.
  • SharePoint backup fails with the “The Attachments column does not exist. It may have been removed by another user” error.
  • Under certain conditions, in the Modern Authentication mode with legacy protocols enabled, Public Folder mailbox backup fails with the “Too many concurrent connections opened. Cannot open mailbox” error.

The update is already available from the VBO console or can be downloaded for standalone install of version 3.0 and higher.