I needed to recover some deleted files from my phone's MicroSD card today. So I dug out an old MicroSD => SD adapter to mount the disk to my Linux machine and start file recovery using testdisk. Disk mounted fine, but it showed up as read-only!

Checked adapter to ensure lock wasn't applied. It was fine. Remounted. Still read-only!

Checked the usual suspects - file and mount permissions - all looked fine. At this point, I suspected the adapter was screwed up. I hadn't used it in years.

Finally, I decided to Google the problem in case I was missing something. And voila...

  1. Slide the switch up and down. Repeat this 3 times.
  1. Let it stay on the Lock position for 30 seconds.
  2. Slide the switch up to unlock the card.
  3. Try to transfer files into the device.