This started happening to me too, it popped up this week. I uninstalled and reinstalled, it seemed to fix it but apparently temporarily. the problem is occurring once again. the program simply wont run.
I've since solved the issue, you need to go to adobe manager, update that, inside the manager udate lightroom, we own lightroom6 but it reads it as cc. once updated the boot up immage for lr changes and it runs fine.
Thanks for your reply. I wasn’t able to follow your instructions, but in trying to do as you described, LR opened again. I got to import my recent photos. I don’t know if messing with the adobe manager was in any way responsible, but thank you for your help. PTL