"There was a problem while playing. Touch to retry" when trying to play offline video I encounter problems when I play videos downloaded from Youtube. I've downloaded 5 videos. Those videos are added to disk. The downloads were all completed successfully, but when I try to play them, it says


  There was a problem while playing. Touch to retry


May I know the reason and how to fix it?
Those videos are added to disk.


How do you know that they are added to disk? and what is mean by disk here? Do you mean external store such as SD card?

If you mean SD card, then that is unlikely as YouTube Offline feature save all downloaded videos on internal storage (and not on disk/SD card), something like below location:

Internal storage/Android/data/com.google.android.youtube/files/Offline/(system generated folder name)/streams


You can check this question for more details on storage of YouTube Offline video location.


  downloads were all completed successfully


Again, how did you verify this? 

The important point is anything you save will be accessible for 48 hours in the offline section on the left-hand sliding menu, of YouTube App. Even if the file is there, YouTube won't list it if it's already expired. The permission is controlled on their server per account basis, to access those downloaded files.

You can try below quick steps to see if you Offline feature is working:


Download at least 1 video and as soon as you finish download Turn-off Internet (3G/4G/Wi-Fi).
Open YouTube App, and go to offline section on the left-hand sliding menu, of YouTube App. 
You should now see this recently downloaded video there, just try to play it. YouTube should immediately start play (remember, we turned off internet in step-1, still app should play video as it is offline and already downloaded on your phone)


Caution: You will lose all Downloaded Offline YouTube videos, when you "Uninstall Updates" of YouTube App.