Sometimes the filesystem itself (rather than the card) can crash. I had this problem on my first photography expedition after buying a new one which came pre-formatted with ExFAT. Fortunately I managed to salvage most of the photos with recovery software (exfat-utils on my Linux computer). I reformatted the card as VFAT (as I've read that ExFAT is more prone to crashes) and have been using it ever since.
Sometimes the filesystem itself (rather than the card) can crash. I had this problem on my first photography expedition after buying a new one which came pre-formatted with ExFAT. Fortunately I managed to salvage most of the photos with recovery software (exfat-utils on my Linux computer). I reformatted the card as VFAT (as I've read that ExFAT is more prone to crashes) and have been using it ever since.