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Release notes for Veeam Backup & Replication 10a Cumulative Patch P20210609

KB ID: 4180
Product: Veeam Backup & Replication 10
Published: 2021-06-10
Last Modified: 2021-10-07
Intended audience for this update

The update on this page is provided as a courtesy to customers who wish to remain on Veeam Backup & Replication 10a for an extended time.

When possible, users are advised to upgrade to the latest version instead of deploying this patch.

This 10a release may only upgrade to 11a or higher.

The build of Veeam Backup & Replication 10a P20210609 listed in this article is only compatible with upgrading to Veeam Backup & Replication 11a ( or higher.

Any attempt to upgrade to v11 ( will fail.


Please confirm that you are running version 10a (build before installing this update. You can check this under Help | About in the Veeam Backup & Replication console. After the upgrade, your build number will be P20210609.

Veeam Cloud Connect tenants: ensure that your service provider uses version 11 P20210507 or later for their Cloud Connect infrastructure before deploying this patch.

Veeam Cloud Connect service providers: this patch cannot be deployed on the Cloud Connect infrastructure servers running version 10a. Please upgrade directly to version 11 instead.

New Features

  • Various product functionality should no longer incorrectly detect Windows 10 21H1 and Windows Server 2022 versions or refuse to work with them. Instead, it will attempt to process them using the existing logic created for previous OS versions. This change does not constitute the official support of these platforms, which is planned for version 11a.

Resolved Issues

  • Backported Microsoft .NET remoting changes from V11 to address a vulnerability (CVE-2021-35971) in the deserialization logic. Veeam would like to thank Markus Wulftange from Code White for reporting the vulnerability and for his collaboration with the mitigation.
  • Object storage: following an extended backup server downtime the retention policy stops cleaning up checkpoints as their immutability period expire; object storage certificate validation does not include a check of whether the certificate belongs to the specified S3 endpoint; changed the blocking “bucket has object versioning enabled” error to a warning to enable registering Backblaze B2 object storage buckets.
  • NAS backup: Improved performance of file share backup jobs when using file proxy servers with a large number of cores.

Known Issues

  • File level recovery on a remote backup console fails with the “Object of type cannot be converted” error. To work around the issue, please install the patch on all remote consoles manually.


This v10a update prevents updating to v11
Installation of the patch on this page (P20210609) will prevent upgrading to version 11 and will only be compatible with an upgrade to version 11a.
If you have 10a installed (GA build, you can apply Cumulative Patch P20210609 using the following update package:


For new installations and upgrades from the previous versions, use the 10a P20210609 ISO image:

More Recent Version Available

Please find the latest version of Veeam Backup & Replication here:


KB ID: 4180
Product: Veeam Backup & Replication 10
Published: 2021-06-10
Last Modified: 2021-10-07

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