Hi Readers,

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.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\v8.0\ClusteredMailboxServer

Delete Watermark reg key & than try uninstall again. (it should work fine now)

Tech Wizard

https://techwizard.cloud

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