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SD card not readable in Catalina

Just bought Sandisk 64GB 170MB/s SD cards but my 2013 iMac running Catalina can't read the card and it doesn't show in Finder and won't mount in Disk Utility.....anybody help please ??

iMac 27″, 10.15

Posted on Mar 23, 2021 12:08 PM

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Question marked as Top-ranking reply

Posted on Mar 23, 2021 12:11 PM

Hi silverfox63,


Unplug the SD card, wait a moment, then re-insert it very quickly into the Mac.


  1. Next, go to Disk Utility
  2. Select "View" > "Show All Devices"
  3. Look for the top, non indented, SD card.
  4. Click Erase, and format accordingly.


If it still doesn't show up,


Cheers,


Jack

5 replies
Question marked as Top-ranking reply

Mar 23, 2021 12:11 PM in response to silverfox63

Hi silverfox63,


Unplug the SD card, wait a moment, then re-insert it very quickly into the Mac.


  1. Next, go to Disk Utility
  2. Select "View" > "Show All Devices"
  3. Look for the top, non indented, SD card.
  4. Click Erase, and format accordingly.


If it still doesn't show up,


Cheers,


Jack

Apr 17, 2021 4:15 AM in response to silverfox63

What I've found recently are two things, both physical in nature:


First the SD cards wouldn't show up in two 2011 Macbook Airs, wiggling the card in the slot made them reappear, the conclusion being just dirty contacts.


Second, the now readable cards could not be written to and all showed up as no_write. The also could not be formatted regardless of the lock-switch position on the cards, or the speed of insertion as suggested elsewhere. I concluded a possible cause could be the lockswitch position sensor in the Macbook's card reader. Being hard to reach and clean I tried putting one or two pieces of tape over the entire lockswitch-channel on the card itself and to my surprise it worked, most of the time. Filling the gap in the lockswitch-channel and then taping it over appeared to do the trick.


Good luck.


If anybody knows how to clean this little switch, as it is probably just a little sticky, please advise.

SD card not readable in Catalina

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