Adprep was unable to set the forest Update revision attribute to %1 on object %2. Status/Consequence Adprep requires access ...

Adprep was unable to set the forest Update revision attribute to %1 on object %2.
[Status/Consequence]
Adprep requires access to the forest Update revision attribute to mark it as prepared. The forest has not been prepared.
[User Action] 
Check the log file ADPrep.log in the %3 directory for more information. Restart Adprep.