Affected versions
This article applies to all versions of Connect Fonts and Suitcase Fusion.
Symptoms
When you open Adobe After Effects, Adobe Illustrator, Adobe InCopy, Adobe InDesign, or Adobe Photoshop, you get an error dialog. Clicking OK causes the application to open normally, but font auto-activation doesn’t work.

Solution
Plug-ins out of date:
The currently-installed plug-in is incompatible with the version of Connect Fonts you are currently running; this can happen if you’ve updated Connect Fonts but haven’t updated the plug-ins. This can also happen if you have migrated from Universal Type Client to Connect Fonts without updating the plug-ins.
You can check the status of the plug-ins by opening Connect Fonts and choosing Connect Fonts > Manage Plug-ins.
Click Install All Plug-ins; you may have to enter your macOS administrator password.
Once the plug-ins have been updated, close and reopen your Adobe Creative Cloud application; the error should not appear and auto-activation will work normally.
Plug-ins up-to-date, but still not working:
Try uninstalling and reinstalling the plug-in for the Adobe Creative Cloud application where auto-activation isn't working.
You can uninstall the plug-in by unchecking the checkbox next to the plug-in, waiting a few seconds, then re-checking the box to reinstall it. You will need to close and reopen your Adobe Creative Cloud application to reinitialize the plug-in once reinstalled. Once that's done, auto-activation should work normally now.