I brought a new micro SD 32GB (sandisk) and soon I put into my Lumia 640XL.

First thing that I tried was move the apps to card, but everything goes wrong and I had to reset my phone.

Later I put the card into my PC to copy some mp3, I take it off (safe) and put into the phone. Nothing happens was like the card was empty.

I go back the SD into the PC and I found a lot of folders named UUUUUUUU.uuu

What is that? A virus? I search on about it, but nothing worth that have fix the problem.

  • 1
    How is the card formatted? WP8.1 will take FAT32 or exFAT cards properly. You should be able to put the card in the phone and tell the phone to format it; after that it should work. You could also try using a different microSD card to see if it's the card or the phone.
    – CBHacking
    Dec 26, 2015 at 8:32
  • Was formatted in FAT32 (the slow way). OK I'll see another SD to make the test.
    – Pablo
    Dec 26, 2015 at 12:03

2 Answers 2


The real problem is that the card is fake, not original. So I've just got my money back and bought a new one.


My card seems fake or faulty also, I was very ready to blame it on my WP but was wrong as my old drive worked well on it. Formatted and all sorts, now using a piece of software to see if it is genuine called 'H2testw'. I will always test cards from dubious places like Ebay now with this software. It also tests Flash drives, is useful.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.