Once your fonts, sets, and users have been migrated to Connect Fonts, you need to remove Universal Type Client and install Connect Fonts Powered By Suitcase. Both font managers use a type core application in the background to activate and deactivate fonts, and the type cores from each application are incompatible.
Uninstalling Universal Type Client for Windows
To uninstall Universal Type Client for Windows, go to Settings > Apps, select Universal Type Client, and click Uninstall. Windows will ask you to confirm that you want to uninstall; click Uninstall.
Once UTC has been removed, go to C:\Users\username\AppData\Local\ and drag the Extensis folder to the Trash.
Uninstalling Universal Type Client for Mac
Download the Universal Type Client uninstaller script from https://cs.extensis.com/fm_uninstall/utc/uninstall-utc.zip. Double-click to launch the script and follow the instructions that appear.
You may get a warning that macOS can't verify that the script is free from malware.
Control-click on the uninstall-utc.command file and select the Open option from the dropdown menu; you will get a different dialog with two buttons. Click Open.
Installing Connect Fonts
For information on installing Connect Fonts for Mac and Windows, go to Installing Suitcase Fusion.
To learn more about what's new and different in Connect Fonts, go to What's new and different in Connect Fonts for Universal Type Server users?