If you are using LR 6.0, go to the menu:
Help >> Updates
Install the 6.1 update.
Thy very much for Your help.
After update the Help goes open correctly.
Thx and regards
I have the same problem, but am already running LR 6.2.1 (Win7 64-bit, tried several browsers). The online help won't load:
Thank you for the link.
I suggest to tackle this issue in future updates.