A recent LG software update seems to have broken the NowTV App and All 4 App on certain LG Web OS TV's.
LG are apparently on the case according to NowTV.
Here's the latest Tweet from NowTV with regards to this subject.
Should you decide not to wait for the LG /NowTV patch fix and go ahead and factory reset your television suggested in the tweet below.
Then just be aware that you will need to re scan your TV channels, log back into any Apps that need your sign in details and if you have customised your picture and sound settings these will be lost and you will have to start again from scratch.
I have same problem two day ago Now TV stopped working on my LG TV I can view the selection but when I try to play it generates an error message. I will probably cancel no doubt millions of LG users will walk away from Now TV and go elsewhere. It is nigh impossible to find any advice from the company.
LG screwed up an update.
Factory Reset the TV, and it should fix it.