We were performing the decommission of Exchange 2007 CCR servers, on all our servers uninstall went fine except one of the CCR, uninstall resulted in below error:
Clustered Mailbox Server Failed Error: Setup previously failed while performing the action “BuildToBuildUpgrade”
On researching We found that there might be watermark reg key because of previous failed check.
Delete Watermark reg key & than try uninstall again. (it should work fine now)