Solving problems with UAC in Windows Server 2012
Suddenly for me, Veeam Backup & Replication started to throw errors while backing up some of my virtual machines. As I have managed to find out, root problem was in that Veeam could not run pre-freeze script to stop some services.
Futher researches showed that UAC denied starting of scripts. When I tried to run script with elevated permissions, stop-start of services was performed without any problems.
The best solution I've found - is to disable UAC at all.
Go to regedit HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system and set parameter EnableLUA to 0.
Unfortunately, you will have to restart complete server to apply new settings.
After rebooting the server, Veeam was able to stop all needed services and make backup correctly.