problem with finding photos

[bertje09]

I just bought me a new computer (iMac) and putted al my photos on an extern disk.

Now I want to join the folder of 2018 to my catalog en Lightroom says that he cannot found any new photo.

They are surely on my extern disk but how can I get these also in my catalog?

[99jon]

It will help us to answer your question if you could provide the exact version number you have installed. 

• Lightroom v3.3; Lightroom Classic v9.3
You can find this from your application menu:
Help >> System Info