This problem has been canvassed widely and I’ve read all of the relevant posts but none of them work for a database I have that just won’t open. It does a couple of peculiar things that may give a clue to people more knowledgable than me.
If I use File>Find & Open, right-click and choose Open data sheet only, I get the beachball spinning endlessly and Menu Meters shows that Panorama X is working away, using 100% CPU (spread across four processors), so it’s doing something - knocking on the door perhaps.
If I right-click and choose the Open with no windows option, nothing happens. Checking with Memory Usage shows that the file has not opened.
In both cases, Menu Meters shows 100% CPU usage (with usage varying constantly on each processor) , the beachball spins and nothing happens - like forever.
If I •Show package contents* and open the data.archive file with TextEdit, I have access to the data sheet which shows the contents, along with lots of (presumably) binary characters. The other files in the package are not very helpful.