How To Fix Accessory Not Supported Ipad Pro Keyboard. Make sure that your iPad and Smart Keyboard Folio or Smart Keyboard are in the Type position and that you have the latest version of iOS or iPadOS. Apple extended the period of warranty repair for the Apple Smart keyboard for iPad Pro 129 for up to three years.
The last tip on this issue is to make sure that the connectors between your external keyboard and iPad are clean. This serial number is located at the bottom of the keyboard. In order to do this you can go to your iPads Settings first.
Then turn on your device.
Rubbing a magnet over all the connectors on both the iPad and the iPad Smart Keyboard also appears to help. You can turn off your iPad Pro by going to Settings General Shut Down. Disconnect and reconnect the accessory to see if the alert goes away. Reconnect the Smart Keyboard Folio or Smart Keyboard.