3 → 4 Upgrade problem ("operation can't be completed")

[Kinsey]

DT3 Pro Upgrade Issue

It’s not recommended to install multiple versions/editions of DEVONthink concurrently, this can cause various issues like this one. Just removing the DEVONthink Pro Office 2 application should be sufficient to fix this.

"global" Inbox DTTG: no sync after upgrade to DT 3. from DT 2

You should not run DEVONthink 2 and 3 on the same account, on the same machine. At a minimum, you should delete the DEVONthink 2 application from the /Applications folder.

Apologies, I obviously misinterpreted the advice re running DT2 and DT3 on the same machine