Just updated to Win 10; I use LR 5.7 on C drive and the photos on an external Drive; Must I reimport the photos and catalog from the external drive?
NEVER Re-import. This is one of the worst things you can do, and will make your problems worse.
Use the catalog file from before the update to Win 10. Just double-click on it.
3 years ago you helped me and I appreciated it then as I do now. I was
worried about reimporting for those reasons. Let me try it (by the
way--three years ago my main problem was a travel drive that was crapping
out! Just my luck)