I have some problem recently, after upgrade to Ubuntu 16.04 I can't read my exfat SD Card anymore.
I double checked, got exfat-fuse and exfat-utils installed, and when I check devices I can see my SD Card as /dev/sdd. However when I try to mount it manually it says error:
$ sudo mount -t exfat /dev/sdd /media/exfat
FUSE exfat 1.2.3
ERROR: failed to read boot sector.