Can't open GS after installing latest version having upgraded to El Capitan

I have just installed the latest version of GS, as I was having problems with the older version since I installed El Capitan OS.
But since the I can’t open GS.
When I start garagesale i get a error saying

“The file couldn’t be opened because it isn’t in the correct format. The file might be corrupted, truncated, or in an unexpected format.”

I seen other earlier posts about going to Library/applicationsupport etc and tried all the GarageSale.sqlite backups, also have removed the copy installed and re-install it and tried to reinstall an earlier version…but the problem remains exactly the same.

I have an external back up drive, but even when I try to revert back to an earlier one…I still get the same message.

What is causing this…and what can I do?