On your microSD card reader or adapter, check if the physical SD card lock is toggled down to protect it from being written. If your SD card is not write-protected but the formatting still fails, possibly, the SD card has some hardware issues. Return it to the manufacturer for some luck.
Method 1. Unlock your SD card physically.
Basically, you can find the physical write protection switch on all standard SD cards. The same applies to your SD card reader. This card lock can be turned up/down to disable/enable the write protection on your microSD card. Therefore, the physical lock should be checked first when you find it unable to format the SD card on Mac.
Step 1. Find the lock button on the SD card adapter that inserted with your microSD card.
Step 2. To disable the SD card write protection, slide the SD card lock up to the unlock position.
Step 3. Connect the microSD card reader to your Mac. Try formatting it now, is it working?
Method 2. Ask for the SD card manufacturer for professional help.
Believe it or not, there are many fake SD cards on the market. Sometimes, even the one you brought on the official website of the manufacturer could have hardware issues. In this case, you can either return the memory card for a new one or go to a nearby manufacturer store for help.
