In preparation for a Unity 4.05 to Unity Connection conversion I ran dbWalker version:4.0.57 and received the following error for 800 or so subscribers
1681:(error) no MWI device found with an alias='MWI-1'
0:(fixed) Added new MWI-1 notification device for subscriber
These subscribers had, and looks like they still have, a working MWI extension, looks the fix is adding a new MWI Extension with the extension blank.
I have tried deleting it but when I run DBWalker again it generates the error and puts it back in. This does not seem to be effecting anything but I am trying to get my data as clean as possible before our migration attempt.