Problems with upgrading lightroom catalog

A few days ago I updated to the latest version of Lightroom, after opening it, a pop-up asked to upgrade my Lightroom catalog. So I clicked the button to do this and the process started, but then something happened and whole Lightroom just crashed. I tried several times to upgrade my old catalog, but every time I did this, Lightroom just crashed. After a few times, I just created a new catalog, so I could do the work I had to do for a client, but I was missing everything...

Today I wanted to get to work on some older photos, so again I tried upgrading my old catalog, but again it crashed several times. And none of the times I get an error notification or anything.

This problem is also only with this particular catalog, cause an older catalog updated just fine to the new system. 

Just to check I downloaded an older version of Lightroom classic and in that version my old catalog works just fine and there is no issue at all. This solution is fine for now, but I would like to be able to use the new version of Lightroom classic with this particular catalog. Anyone any suggestions or a solution for this problem? And using a new catalog is not an option, cause this will mean that I'm missing hundreds of photos...