"Unknown error has occurred" app store

[matteo76]

Iphone 4, iOS 6
Problem: i cannot sign in to app store with valid apple id and correct password neither via app store app or via settings. Network 3g and wifi work ok in other application. I tried with other account and siuation is the same. I can sign in to iCloud on PC. What is happening please?

 

[KeithLiu]

I encountered the same issue when I upgraded my iphone4 to ios6, I tried many times and it worked at last. So try more times.