After the transfer to a new computer (MAC), the problem with the error message has occurred. The vault can be decrypted, but does not display any data.
I had the same problem on a brand new MacBook Pro with OSX 10.13.6 and I found the solution in this posting:
You have to edit the file /etc/hosts . In my case, it was empty and i had to add these two lines:
That’s it, works perfectly now!