KB ID 0001228
Problem
On the tail end of an Exchange 2010 to 2016 migration last week, I needed to decommission the old Exchange 2010 server. It would not let me remove the mailbox database, as it had a ‘move-request’ that it thought had not completed, (for the administrator account). However if I tried to delete the move request from the EMC this happened;
Error
Failed to communicate with the mailbox database
MapiExpetionNoAccess Unable to open message store
(hr=0x080070005, ec=-2147024891
Solution
Even trying to remove the move request with PowerShell failed. In the end I had to remove the request in ADSIEdit.msc.
Windows Key+R > asdiedit.msc > Connect to > Default Naming Context > DC={your domain}, DC={your domain extension} > Navigate to the user affected > Properties > Filter > Show only attributes that have values.
Locate the following two values and clear them;
msExchMailboxMoveFlags
msExchMailboxMoveStatus
This is enough to remove the failed mailbox move request, but if you’re nervous, then just refresh the move request section and it should disappear.