well it had to happen went out today ,to do some flying in new places,found a lovely rural setting with great views in the middle of nowhere,got permission to fly from a friendly land owner and got set up to fly ,once all was powered up the app screen informed me that there was no SD card in the mav of course when i checked it out there was indeed a SD card fitted,powered down everything and took out the card gave it a wipe and blew gently into the slot in the drone then put the card back in after starting it all up again the no SD card message had gone went to format card in settings, but when i did this it said no SD card formatting failed this card has done over 250 flights without any issues guess it was just worn out, but of course the one thing i did not have was a spare SD card with me so flying was out ,found a card in a supermarket some 30 miles away, and after inserting it all was well again,as you can guess i will be carrying a spare card in future