I had my RAW files and Catalog on a 1TB external hard drive that I worked from. I copied all of the RAW files to a new 4TB drive as I had nearly filled the old one. I want to use the old catalog (containing my edits for each photo etc) to review at a later date, but when I moved the catalog file over to the new drive, all of the photos are missing from the catalog. I understand this to be because the original file directories are kept. These can be changed through Lightroom for individual files of photos, but can I find all photos at their new location on the 4TB drive without having to do this manually for all of the 20,000+ plus images?
Please see these instructions, particularly Figure 4 and associated text: Adobe Lightroom - Find moved or missing files and folders
but when I moved the catalog file over to the new drive
Also, I would recommend putting the catalog file on an internal disk (is that where it was before?), not on an external disk if at all possible. There are some situations where you want to put the catalog file on an external disk, but you haven't really stated any of those reasons.