http://samba.2283325.n4.nabble.com/Can-t-create-users-with-RSAT-quot-An-error-occurred-Contact-you-system-administrator-quot-td4680227.html I had the same problem as stated in this thread. Wanted to follow up with my results. Server: CentOS 7.1503 Version 4.1.17-SerNet-RedHat-11.el7 Windows 8.1 Pro x64. Updated through May 6/2015. RSAT tools installed: Windows8.1-KB2693643-x64. Initial testing trying to create a new user in Samba 4 provisioned domain. Logged in as Administrator --> open Administrative Tools --> Active Directory Users and Computers ---> internal.example.com ---> Users container --> Create a new user in current container failed with error: An error occurred. Contact your system administrator. Per the linked thread, I uninstalled Windows Updates KB2992611 and KB3000850 and restarted Windows client. Tried again to create and configure a new user in the Users container and now works. I need more review to understand the Windows Updates and the "fix" provided by them, but removal appears necessary to unblock options needed in Windows Admin Tools --> Active Directory Users and Computers.