SD flash card READ-ONLY all of a sudden I have a MacBook Air running Yosemite.

I have an external SD drive that I save files to frequently.

Info on SD drive says it's READ-ONLY all of a sudden?  I am the ONLY person that uses this drive and it worked literally minutes ago!
Some SD cards' firmware will lock the device to read-only if any write error occurs.

If this happens, the only solution is to copy all data off it &amp; discard.

SD/flash is not worth the effort of trying to fix, once it starts to go wrong.

Things to try…


Double-check the physical lock has not been flipped by accident.
Reboot the computer &amp; try again
Try it on another computer/device
Once you have all existing data copied from it, attempt to format.


If none of this is successful, throw it away.

I work with hundreds of (admittedly very cheap) SD cards for work, &amp; this is our standard practise if they start to fail.

Golden rule
Never store any important data on SD without having a safety copy on some more reliable medium.
I'd even extend that to - if you have to use SD to carry data from one machine to another - home/work etc - use 2 cards &amp; keep them manually in sync with your work.