For non-admin Remote Desktop Users in Windows Server 2012 R2 they get this dialog when they try to do something that is not allowed. Is there a way to stop this? I've disabled the policy "User Account Control: Run all administrators in Admin Approval Mode" but it does not help.
you stated, that for non-admin users... so what do you expect from a "Run all administrators.." policy? you have to disable UAC for all (my guess)
I've tried the other more appropriate polices, they do nothing too. "Behavior of the elevation prompt for standard users" set to deny or whatever it is, it still shows the prompt.
UAC is working as designed. The user tries to do something "not allowed" and it stops them. If you want them to be able to do a particular thing, look at the permissions related to doing the thing. For example, if they are getting the popup when trying to copy files to a folder, make the user a member of a group which has write permissions on that folder. If you want the users to have unlimited access to everything on the machine, make them members of the administrators group. I do not recommend this option.