Ah! I was pretty sure that was not a Calibre created file.
Acronis allows partial extraction: DO NOT place direct into any WORKING (one with any books) Library . Only restore as a Complete Library folder.
You can always us CALIBRE to move (
copy to Library) books to other libraries
It has been a long time since the structure changed enough to make it incompatible with current releases. You should be good to go.
