Hi @charry​, Can you see if a file named qt.conf exists in your FMEinstall directory (i.e. C:\\Program Files\\FME). If it doesn't exist, please download the installer again, and reinstall FME Desktop.

If qt.conf exists, open it in a text editor, check the value of Prefix. If the value is set to "." then change it to your install directory (i.e. C:\\Program Files\\FME) or vice-versa.