On Mac OS only I have encountered that issue too.
Again, engineering needs the logs to investigate.
Do let me know the log numbers when you send them to asupport in the final step!
I am now trying to migrate our custom installer using WiXToolset on Windows that relied on ExManCmd to UPIA and I am running into an issue when a batch file being run during install just hangs after issuing the command to remove previous extension:
C:\Program Files\Common Files\Adobe\Adobe Desktop Common\RemoteComponents\UPI\UnifiedPluginInstallerAgent>UnifiedPluginInstallerAgent.exe /remove "com.cinemagrade"
Removing com.cinemagrade
As you can see, I get the message about extension being removed but no resolution and no status.
The same bat file works fine when ran from the command-line.
Installer is in the elevated mode.
Any thoughts/suggestions?
A bit late to the party, but UPIA --install gives me Request failed with status = -641 as well, and I should be logged on in the CCD (at least thereās my ugly face in the top-right corner)
Iāve tried to pass around a test ccx that doesnāt belong to the CC Marketplace, and the person wasnāt able to install via double-click. Nor with right-click, Open With, UPIA (āThe document ā¦ cannot be opened, CC cannot open files of this typeā).
UPDATE: A restart seem to have solved for them!
Surprisingly, I tried myself a couple of times and while the double-click always worked, Open With didnāt (always). When the CCD was running it seemed to be ineffective. But then I restarted and it went fine. ĀÆ\_(ć)_/ĀÆ
So in the end they have solved, and I have discovered that I canāt run UPIA 
CCD 5.9 ships with UPIA 1.6.0.34 which should clear up some of the -641 errors. Iām working on a list of updates to share, (but was sidetracked by MAX).