I have 4 Compact flash cards one of which was in the camera EOS 40D and was working
I removed the flash card to transfer data to my Win 11 when i replaced the flash card back into the camera there was a message "CF card not formatted Format card with this camera" which i did and another message "Cannot format change the CF card" which i did.
Still the same messages
I then formatted all 4 cards through the computer and got the same messages on all 4 cards
The cards are
Canon FC-32M, the original card
ScanDisk 256MB
Extreme 128GB 120MB/s which was the card i was using in the camera
Extreme Pro 32GB 160 MB/s brand new
I have checked the pins in the card slot and they are fine
My feelings are that its the camera or camera soft/firmware as the new card should have just slotted in
Any help i would be grateful