"this file cannot be found"

It seems there are not all data was migrated to the new computer. Or the drive and/or folder whre the images were stored the images were changed. 

Check if your find the appropriate images in the Windows Explorer.

Do you have still access to the old computer? If yes, check where the images are found on this machine.

If you find the images only on the old computer transfer these to the same location (drive/folder) on the new computer.

Here you'll find a article with good informations about moving lightrooom to a new computer: 

https://www.lightroomqueen.com/how-move-lightroom-to-new-computer/

Hey @Memphis3605, 

Hi there, and welcome to the Lightroom Classic Community! It sounds like you might need to relink your images, but I don’t want to assume too much just yet. Could you share a bit more about what you’re seeing? It would also be super helpful if you could include your system info. You can find it by going to Help > System Info in Lightroom Classic, then copying and pasting that into a text file and attaching it here.

If you can, please include a screenshot of the issue, too—it really helps us see what’s going on.

In the meantime, here’s an article that might point you in the right direction: https://adobe.ly/4mS9bRV

Looking forward to hearing more so we can get this sorted!