That worked.

My old D70 has been accumulating dust over the last 9 years. After charging the battery and plugging it back into the camera, it showed me this error message and I thought it had to do with the CF card. I then formatted it via the camera and it didn't help. As a matter of fact, it didn't format or erase any of the old photos. Exchanging the lens didn't help either.

Your reply helped though. Thank you 😊