KB1788: Credentials Test or Job Fails ... - Veeam Software
https://www.veeam.com/kb178808.07.2013 · Cause Veeam Backup & Replication uses the VIX API as a network-less connection method to perform Guest Processing when a VM cannot be contacted directly via RPC. Due to the way VIX operates, it is blocked by Windows User Account Controls. Also, because VIX relies on VMware Tools, if VMware Tools is out of date, issues may occur. Solution