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Veeam Backup for Microsoft Office 365 4c cumulative patch KB4099


Please confirm you are running Veeam Backup for Microsoft Office 365 version 4c (builds,, prior to installing this cumulative patch KB4099. 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

Cumulative patch KB4099 addresses the data loss issue described in the KB4103 and includes a set of other fixes, the most significant of which are listed below:

Resolved Issues

  • Under certain conditions retention policy mistakenly cleans actual Exchange backup data from Jet-based repositories set with snapshot-based retention of less than 2 years.
  • For SharePoint backup, creation of the new 2021 repository database triggers full synchronization instead of incremental backup on the next backup job run.
  • SharePoint and OneDrive backup may fail with “(500) Internal Server error” or “(400) Bad Request” error.
  • Archive mailbox backup may fail with “Failed to access archived message folder root. SOAP header Action was not understood” error.
  • SharePoint backup may fail with “Invalid MIME content-length header encountered on read” error.
  • List items restore may fail with “Cannot find corresponding Content-Type for: %version%. Original ContentTypeID” error.
  • Executing the Export-VEXItem cmdlet may fail with “Method not found” error.


To install the cumulative patch KB4099:

  1. Download
  2. Execute VeeamBackupOffice365_4.0.1.625_KB4099.msp as administrator on the Veeam Backup for Microsoft Office 365 server.
  3. Execute VeeamExplorerForExchange_4.0.1.625_KB4099.msp as administrator on each machine where Veeam Explorer for Microsoft Exchange is installed.
  4. Execute VeeamExplorerForSharePoint_4.0.1.625_KB4099.msp as administrator on each machine where Veeam Explorer for Microsoft SharePoint is installed.

If there are any remote proxies in your environment, please update those as described here.

MD5: eff8bfe1603080f1e64bdac7fdfc94ea
SHA-1: d0f7174c57e237c6cf4ac7a2cc69ae0cc98dc298
Veeam Backup for Microsoft Office 365 4.0
Last Modified:
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