I got the same error as Hans Leibold did almost three years ago.
This ODB++ file was created by Altium Designer 17
I tried to import the .tgz file
The problem is in the misleading Import Job dialog. It has a box for Input File and a box for Path. I put the path in that box and the filename only in the Input File box, using cut and paste. I hit the OK button and that is when I got the error.
When I used the browse function of the Job Input dialog … and pasted the path into the file name window (rather than browse all the way through my directory structure), ODB++ Viewer gave me a selection of file choices. I selected the .tgz file and hit OK.
This time, no error. ODB++ Viewer opened the job and it is working very well now.
It’s disconcerting that no one responded to Hans in almost 3 years. This was very easy to solve with a little fish and fumble.