Make sure you are running Veeam ONE version 9.5 updates 3, 4 or 4a (builds № 126.96.36.19901, 188.8.131.5266 and 184.108.40.20687) prior to installing this update. You can check this under Help | About
in Veeam ONE console. After upgrading, your build will be version 10.0.0.750.
If you are running Veeam Availability Suite, upgrade Veeam ONE first; Veeam Backup & Replication must be upgraded after Veeam ONE .
Before you apply the update, make sure you have a full backup of Veeam ONE database (how to backup Veeam ONE database