We’ve already covered what to do when instup.exe runs for a long time, here, if you’re in a hurry, rather than following the steps mentioned in that, simplest solution has been offered here. Now, when you try to kill it, you’ll get a unable to Terminate process dialog saying ‘The Operation could not be completed. Instup.exe of Avast is downloading and updating virus definitions in the background, you can see this process running in the task manager. You may want to know another mysterious Windows process Avast runs Fixing Avast’s ‘Setup is already running’ error Please try to start the setup later’ and offers the ‘View log’ button in it, when you open it, ‘Avast Log Viewer’ appears and it doesn’t provide any information to troubleshoot the issue, let us see how to fix this and remove Avast antivirus without any problems. When you try to uninstall Avast to reinstall it or to install another antivirus on your computer, uninstallation doesn’t start, instead a dialog appears on the screen saying ‘ Setup is already running.