Get this error when installing even without any other applications open. This relates to the **XProtect Management Client** being open, on Windows Server this can be open in another users session. ![[z_img/a813a863f1c7266742ca52008807652b_MD5.jpeg|600]] Open Task Manager, right click the taskbar and click Task Manager. If this looks like below, click [More Details] ![[z_img/bb6bef87a11d39482a0b9cf76f0021fc_MD5.jpeg|400]] Go to the [Details] tab and scroll down to **VideoOS**, these are all Milestone XProtect processes. You need to find and right click **VideoOS.Administration.exe** click [End Task] ![[z_img/8994f6a86830abef3ad21c91db90b88d_MD5.jpeg|500]] Click [End process] ![[z_img/1de55b698d39945735479206bf3616fc_MD5.jpeg|350]] Click [Ok] in the installer prompt to continue. ![[z_img/bf3d89088f02698228370c7d9dff5fda_MD5.jpeg|450]]