I'm not able to use my SD card on my MacBook Pro after I upgraded the OS to El Capitan. I tried to reset PRAM without success. Consider that if I put the SD card on another Mac it works perfectly. Any suggestions?
I would install the older OS to another USB drive so that you can verify that the new OS is really causing the issue and it's not a hardware failure.
When you boot to the old OS (hold option key when booting to choose which OS of the ones connected) run
diskutil list to check the filesystem on the SD card.
It's unlikely that it's a format that's no longer included in the new OS. It's more likely that you'll find the card itself faulty or the hardware has changed and needs to be cleaned (lint can obscure one pin connector) or repaired. You can also get a USB to SD card reader to avoid needing to reinstall the old OS just to eliminate the SD card reader as a potential source of the problems on the Mac with the new OS.
Remove the SD card, reboot the machine and don't put in the SD card until it is completely rebooted. Worked for me.
I've just encountered the same issue, and after some research found that the problem is that OS X does not load the SD kext (Kernel Extension - a driver) for whatever reason. Loading it manually resolves the issue.
- Eject the SD card
- Open Terminal
sudo kextload AppleSDXC.kext(enter your password for sudo access)
- Insert SD card
After this, my SD card appeared in
diskutil list and in the GUI Disk Utility and was mounted in Finder. Annoyingly this has to be repeated after rebooting, or you can automate it.
I was able to fix this by doing the following:
starting my mac in recovery mode by holding cmd + opt + r
selecting disk utility
clicking mount for my SSD
clicking first aid
restart my mac