Category list is empty

[Fres]

Today I noticed my category list does not show any more. I have to admit that I did receive error messages in the past (catalogue file could not be opened) which I could not solve, but I could see the list I made all the time. But today I could not find any category at all. I attach a screenshot of the error.
I checked the location of de catagory db which seems OK to me (some 145Mb last change today).
What could have gone wrong and how could it be to repaired?
I make a daily backup of my Xnview.db

[xnview]

could you send us the xnview.db by mail?

[Fres]

Dear Pierre,

Sorry for the delay in reply to your reaction on my post, but I had some serious personal priorities higher than working on my photos.
I'll be glad to send my Xnview db by mail but what is the address and what reference do I give it?
Frans

[user0]

what is the address

run app, press F1 - find email address

however, you can try to do it yourself:
XnViewMP - catalog - relocating folder

[Fres]

Thanks user0 for your assistance. But I haven't changed the base location of my photos for a long time. So I see no need to apply the conversion of the path as you suggested.
Only recently the category list is empty. When I now look at the files presented in the cateloque they all have a size of 0 bytes. Re attached screenshot.

[Fres]

I have sent the Xnview.db via Wetransfer, but the file hasn't been downloaded sofar. Ultimate date is TODAY!

[xnview]

I have sent the Xnview.db via Wetransfer, but the file hasn't been downloaded sofar. Ultimate date is TODAY!

Sorry please send me it again?

[Fres]

Will do

[Fres]

Please refer to screenshot sent of filelocation and find attached screenshot with (part of) files in location on my desktop I:/Foto's/Nikon/Basis-JPG/Nrd_Spanje (more files and with content than presented by Xnview; only 14 files)
Frans