I Can't Cast YouTube Videos From My Mobile Device to My Android TV

Each of these steps represents a possible solution to this issue, check to see if the issue is resolved after completing each step. 

1. Update the TV to the latest software. 
   For how to update, refer to: How do I perform Firmware/ Software Updates for my Android TV™? 
    
2. Reset the TV and the mobile device.
   For how to reset the TV, refer to: How to restart (reset) an Android TV?
    
3. Use the following procedure to uninstall updates for Android System WebView and Chromecast built-in.
   1. Press the HOME button on the remote control.
   2. Select  Settings.
   3. Select Apps.
   4. Select Android System WebView.
   5. Select Uninstall updates, then Select OK.
   6. Press the BACK button on the remote control to return to the Apps screen.
   7. Select Chromecast built-in.
   8. Select Uninstall updates, then Select OK.

   After uninstalling the updates, reset the TV and update the two apps above to the latest version from the Google Play store.
    

*Android, Android TV, Chromecast built-in, Google Play and YouTube are trademarks of Google LLC.