I searched some time in web for solution, almost all of solutions which i found involved connecting my iPhone to PC. BUT i found an solution without connecting my phone to my computer. okay:
"Tap to retry the download and as it’s attempting to download it again hit the pause button (you have to be quick). Once it was paused I hit the button again to resume the download and it successfully completed. "
I hope this helps some of you to fix this bug ;)
