Please confirm that you are running version 10a (build 10.0.1.4854) 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 10.0.1.4854 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.