I can’t make a back up of the catalogus

Hello,

Since last week I can't make any back ups anymore of mine catalogus when I shut down Lightroom classic. It starts with the back up and stops after a few seconds. Then it takes a while before I can shut down Lightroom because it's doing something but I can't see what it is.  I have the latest versie of Lightroom.

Can somebody help me with this problem so that I can make back up's again.

kind regards, 

Johan van Gool