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Veeam Backup for Microsoft Office 365 5b cumulative patch KB4124


Please confirm you are running Veeam Backup for Microsoft Office 365 build prior to installing this cumulative patch KB4124. You can check this under Help and Support > About in Veeam Backup for Microsoft Office 365 console. After upgrading, your build version will change to

As a result of on-going R&D effort and in response to customer feedback, cumulative patch KB4124 provides a set of enhancements and bug fixes, the most significant of which are listed below:


  • Optimized operations with local cache to improve the performance of SharePoint backup to an object storage repository.

Resolved Issues


  • Adding Office 365 organization with modern app-only authentication fails with “Invalid Exchange Web Services response” error.
  • Backup job session processing rate may be displayed with a negative value of -1.
  • In the backup job wizard, some users may not be displayed and available for selection.


  • SharePoint backup fails with “An item with the same key has already been added” error.
  • Exchange mailbox backup fails with “The specified object was not found in the store” error.
  • Exchange mailbox backup fails with “Mailbox is already processed by another job” error.
  • Under certain conditions, Exchange mailbox backup fails with “One or more of the specified parts could not be found. The part may not have been uploaded, or the specified entity tag may not match the part's entity tag” error.
  • Exchange mailbox backup fails with “Arithmetic operation results in an overflow” error.
  • In on-premises Exchange organizations, public folder backup fails with “Value cannot be null. Parameter name: source” error.
  • Microsoft Teams backup may fail with “400 - Bad request - Value cannot be null. Parameter name: token” error. For more details, see KB4123.
  • SharePoint personal site backup may fail with “Failed to resolve personal site owner. A user may not have a valid Microsoft Office 365 license with a SharePoint plan enabled” error.
  • After moving existing OneDrive and SharePoint backups to an object storage repository, a new backup job targeted at this repository may fail to create restore points.


  • OneDrive and SharePoint items restore with modern auth with allowed legacy protocols may fail with an authentication error.


  • In the License Overview report, a user display name is displayed instead of a UPN.


To install the cumulative patch KB4124:

Make sure all jobs are stopped and disabled.

  1. Download
  2. Execute VeeamBackupOffice365_5.0.1.207_KB4124.msp as administrator on the Veeam Backup for Microsoft Office 365 server.
  3. Execute VeeamExplorerForExchange_5.0.1.207_KB4124.msp as administrator on each machine where Veeam Explorer for Microsoft Exchange is installed.
  4. Execute VeeamExplorerForSharePoint_5.0.1.207_KB4124.msp as administrator on each machine where Veeam Explorer for Microsoft SharePoint is installed.
  5. Execute VeeamExplorerForTeams_5.0.1.207_KB4124.msp as administrator on each machine where Veeam Explorer for Microsoft Teams is installed. 
  6. If there are any remote proxies in your environment, please update those as described here.
  7. Enable all jobs back.
KB ID: 4124
Product: Veeam Backup for Microsoft Office 365 5.0
Published: 2021-03-05
Last Modified: 2021-03-26
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