Copying locked OST files

When trying to copy ost files that were in use I was running into the following error:

esentutl.exe /y /vss <file_to_copy> /d <file_to_save_as>

Operation terminated with error -1 (JET_wrnNyi, Function Not Yet Implemented) after 4.390 seconds.

The reason being, Windows VSS engine ignores Outlook's .OST files.

To work around this, the OutlookOST value must be deleted from HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot.

reg delete HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot /v OutlookOST /f

Once this is done, the file can be copied.

esentutl.exe /y /vss <file_to_copy> /d <file_to_save_as>

And then the value can be restored when the file is done being copied.

reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot /v OutlookOST /t REG_MULTI_SZ /d $UserProfile$\AppData\Local\Microsoft\Outlook\*.ost /f