If the SD card fails verification, it could be due to:
1. The card is damaged or faulty
2. The card is a counterfeit and the stated capacity does not match the actual space on the card
Try a different card, a different-sized or brand of card. If multiple cards fail in the same way, make sure the card is seated properly in the card slot. If using a USB card reader, make sure the cable is good and the USB connection is seated properly in the Mac's USB port.