I checked out several of the previous posts and none seemed to address my issue. I have two PCs, Dell is running Win 10 (1608) and HP is running Win 10 (1511). Can't upgrade the HP to 1608, but that's another story!
After installing the Anniversary Upgrade, set up HomeGroup on my Dell and received a password. Recorded it. Set up items to be shared.
Tried to attach my HP to the Homegroup. At first was advised that no other PC was identified. This later changed to "Windows detected another homegroup on your network." Clicked Join Now button. Asked for homegroup password. Entered the one from the Dell setup and clicked Next. After several minutes delay, got message "Windows no longer detects a homegroup on this network. To create a new homegroup..." I ignored this suggestion as I don't want to set up another homegroup.
I hope someone can help me figure this out, because I'm tired of transferring files via USB drive!