Error Response: the specified slot is already occupied
Solution: Unplug your PS4 and plug it back. To turn on the PS4 into Safe mode, Press and Hold down the power button on the PS4, until the console beeps twice. Connect your controller with a cable and select "Rebuild Database". If this doesn't solve your problem, try contacting Sony directly or a video game repair shop for further help. Please post below if you were able to solve the issue yourself to help others.