@agbor this error happens because of a bad connection between the contacts of the memory card and the camera. Try the card in a memory card reader and see if it works, also backup all your files. Then try to clean the contacts of the card with a pencil eraser. You also want to insert and remove the card a couple of times to see if it starts making proper contact. Wiggle the card a few times to see if the error will disappear. Ultimately you could also try a new memory card.