Backups to DD Boost Repository Fail After Upgrading to Veeam Backup & Replication 12.1.1

Jobs or tasks interacting with a Dell Data Domain repository accessed using DD Boost failed after upgrading to Veeam Backup & Replication 12.1.1 with the following error:

Failed to initialize DDBoost Library (Veeam.Backup.Common.CCppCOMException) in use. Err: 5012

This issue occurs because the Veeam Installer Service was unable to replace the existing VeeamDeploymentDll.dll with the newer one during the upgrade.

When this occurs, the following error can be found within the C:\ProgramData\Veeam\Backup\Svc.VeeamInstaller.log log file:

ERR |Failed to delete [C:\Windows\Veeam\Backup\old_12.0.0.1423_VeeamDeploymentDll.dll] file.
>>  |boost::filesystem::remove: Access is denied: "C:\Windows\Veeam\Backup\old_12.0.0.1423_VeeamDeploymentDll.dll"
>>  |An exception was thrown from thread [n/a].

Consequently, the old VeeamDeploymentDll.dll is unaware of the updated DD Boost library (libDDBoost.dll) included with Veeam Backup & Replication 12.1.1, which causes initialization errors.

Restart the machine assigned to as the Gateway Server for the Data Domain Repository.

Alternatively, for larger environments where multiple Gateway Servers are present, Veeam Technical Support can provide a private fix (reference Issue ID 661804) that allows running a cmdlet to restart the Veeam Installer Service (VeeamDeploySvc) service on the Gateway Servers remotely.