I am receiving the “accessory not supported” message on my I pad when I open

You didn’t clarify which keyboard, but that’s fine. I occasionally get the same message while using my Smart Keyboard. It’s a very simple fix, where the iPad wasn’t properly able to read the “USB Accesory” that you are connected to, which is the keyboard via the smart connecter. Just take the iPad of the keyboard and clean up the smart connector areas on both devices if needed, then put it back on again. This should solve the problem. If you’re using the Magic Keyboard and at the same time the pass through charging, take out the charger and put it back in again, but properly. This always works for me, but if it doesn’t work for you, just say.

Are you connected to a charger, Smart Keyboard, Magic Keyboard, Apple Pencil, etc? If you’re not connected to anything, then its a completely different problem.

I need to clarify once again. Are you using an Apple Keyboard or a 3rd party keyboard? This is important stuff. Sorry for the late reply, I’ve exceeded the posting limit and had to wait.