A SharePoint 2010 server farm with FAST had the upgrade-status “failed”.
After performing numereous attempts to get it back in status “succeeded” I did found a workaround.
Clearing the cache didn’t solve the trick (http://support.microsoft.com/kb/939308).
When you execute the PSConfig command for upgrading (“psconfig -cmd upgrade -inplace b2b -force -wait”), the command will perform 4 steps: within the first he will stop the administrative and timer job service. In my situation, he stopped always on step 4: he couldn’t start the service back. The diagnostics log mentionned that an update conflict has occured …
I thought, let me manually kick those services while the upgrade proces is in step 2, just before he will try to create his timer job for upgrading and auto-kick start the service (nothing to lose :-)) I did it, and it worked 🙂
So stupid, but yeah…
Another Solution (credits go to Balasubramanian Murugesan)