Turn off the PS4 completely
Unplug the power cord from the console
Wait at least 30 seconds
Plug the power cord back in
Turn on the PS4
For a deeper cache clear, turn off the PS4 again
Unplug the power cord for 1 to 2 minutes
Press and hold the power button on the console for 10 seconds while unplugged
Plug the power cord back in
Turn on the PS4
Rebuild the database in Safe Mode if needed
To enter Safe Mode, turn off the PS4
Press and hold the power button until you hear two beeps
Connect the controller with a USB cable
Select Rebuild Database from the Safe Mode menu