Plesk 8.1 restore

I have tried to restore a Windows Plesk 8.1 backup file but it failed with a "Failed to migrate virtual server : Not a Plesk 8 backup file : Unknown compression format"
Is there any workaround to this problem ?
My main concern is mailbox migration, of course, since everything else can be, easyly, done manually.

Why not file a bug, so we can fix it? :wink: