This message then appears on my screen without having anything connected

Hello, Heartachelord.

Thank you for visiting Apple Support Communities.

I understand that you are receiving an alert regarding accessory compatibility when the device is unplugged. I would start with making sure that the Lightning port is free of any debris and not damaged. Next, try going through the troubleshooting steps in the article below.

Accessories

Get help if you accessory isn't working:

• See About iPhone, iPad, and iPod accessories and Resolve issues with Phone, iPad, and iPod touch accessories
• Get help with your stereo headset's buttons

Issue not solved

If you still have an issue with your device, contact Apple Support.

Get help with hardware features on your iPhone, iPad, and iPod touch

Cheers