Mailbox Move Error – ‘Couldn’t switch the mailbox into Sync Source mode’

KB ID 0000795 


While attempting to move a mailbox between sites last week I got this;

Couldn't switch the mailbox into Sync Source mode.

Error details: Couldn't switch the mailbox into Sync Source mode.
This could be because of one of the following reasons:
Another administrator is currently moving the mailbox.
The mailbox is locked.
The Microsoft Exchange Mailbox Replication service (MRS) doesn't have the correct 
permissions. Network errors are preventing MRS from cleanly closing its session 
with the Mailbox server. If this is the case, MRS may continue to encounter this 
error for up to 2 hours - this duration is controlled by the TCP KeepAlive settings 
on the Mailbox server. Wait for the mailbox to be released before attempting to move 
this mailbox again.


I knew no one else was attempting to move it, and I had full exchange permissions.

In my case the two sites with Exchange were joined together with a site to site VPN, the error message was giving me a hint (though a cryptic one) with the ‘Network errors are preventing MRS‘ comment. What I needed to do was increase the ‘Keep Alive’ time for it to complete.

Note: I increased the keep alive time to 1 hour, most posts I’ve seen recommend 5 minutes, it’s up to you, I was running my mailbox moves overnight and I didn’t want to walk back into carnage. Just REMEMBER to DELETE the registry entry when the mailbox moves are compete!

1. Before you can attempt to move the mailbox again you need to remove the move request, either graphically (Exchange 2007/2010) from the Exchange Management console > Recipient Configuration > Move Request > Locate and delete the move request, or from PowerShell;

Remove-MoveRequest {Username}

2. On the source mailbox server, Start > Run > Regedit > Navigate to the following registry key;

HKEY_Local_Machine > System > CurrentControlSet > Services > Tcpip > Parameters

Create (or edit if it’s already there) a 32 bit DWORD value.

Create New DWORD

3. Call the value KeepAliveTime and set it’s value to 3600000 (Note in milliseconds that’s 1 hour), if that’s to rich for you use 900000 (15 minutes).

KeepAliveTime Registry

4. Repeat the process on the destination mailbox server (and any hub transfer servers that will be in the ‘path’ of the mailbox move).

KeepAliveTime Mailbox Move

5. Don’t forget to remove these changes when you are finished.


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Author: Migrated

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