Updated to 'required' firmware and after upgrade I received the message "Strong Wireless Interference, fly with caution".  This is a new warning which I have never received before and I am flying in my normal location from which I've done dozens of flights without a problem.

Can the updated firmware have caused this?

It's my experience that the message comes when I've turned on WIFI on my tablet. Possibly the message may also come from using the phone! Put your phone in airplane mode and everything should be as before the update.

Regards Leif.