I find it is now 5 years since this card type (micro sdxc 64GB) is causing problems.
I bought 3 in the last 2 years, without really informing / documenting the problems of Sandisk cards very seriously before. Two of them died. Same symptoms: it can not be written on either (neither move, nor delete, nor format, nor low-level formatting, no change to the partition type …). I’ve tried many softwares (including SD Card Formater from SD org recommended here). I even tried the diskpart command to change the card attributes … The card has exactly the same behavior in Windows, in Android phone, or in Canon camera. Any changes to the card content are blocked, but reading can be done.
Under these conditions, I can say that there is a lack of respect for customers from SANDISK. 5 years is too much. Obviously, it is a physical defect that requires redesigning this type of card and withdrawing existing ones from the market. Anyway, I will not buy Sandisk anymore.
On the card packaging it is written “not intended for sale in the U.S.” And “No warranty” for this market! So … probably Sandisk thinks it’s good for the REST of the world.
