All of my SD cards are suddenly giving this erroneous Read-Only message. It started wit the 10.10.3 update of my MacBook Pro. Before that they worked fine. I have cards from different brands and sizes. The problem is with the MacOS X update having a bug. Older computers that do not have the 10.10.3 update do not have the problem mounting, reading or writing to these cards. All of the cards have their tabs in the unlocked position and worked before. Solutions? Known 10.10.3 bug?