Why did the Windows 10 Upgrade ruin my micro SD card?

[Windows Central Question]

The download of Windows 10 on my Lumia probably damaged my 64 GB SD Card as it misfunctioned during the upgrade. Shortly after the download was finished, the phone rebooted and an error occured, stating that the SD Card could not be accessed and that I should retry the upgrade. However, the SD Card was already unusable at that time.

Now I am not able to upgrade to Windows 10 and I tried all possible solutions to format my SD Card (my Lumia and photo camera do not recognize it, my PC recognizes only 31 GB and is not able to format it).

 

[TheChazas]

Strange, never heard that updating would ruin an SD card.

 

[AndyCalling]

Sounds like you have a forged SD card there. What is sometimes done, is that a lesser capacity card (say, 32gig) is cunningly reprogrammed to report itself as a larger card (say, 64gig) which works fine until you try to write to a bit of it that isn't really there. Then all hell breaks loose. So now your system gets confused as it can only use 32gig of space on a disk that claims more. Hence it is now reporting half the space but can't work out how to make it work properly. In this case, the update did not destroy your SD card, but revealed the scam due to trying to write a large lump of data to it. I hope I'm wrong, but it sounds very much like you've been scammed.

 

[Jonathan Butt1]

Theme thing happened to me. I ca see the SDcard in MY surface pro4 but its not visible on my Phone. The bugger is that its a brand new phone (650Dual sim) and the SD card was also brand new.
The update happened last night and I Woke to a windows logo hung at boot up. The card hasn't been usable sine then and I did both a hard and soft reset. he second of which I'm restoring from now.
Except that my card is showing full space and since its a san disk I doubt its forged. Any thoughts on how to get it back?

 

[Guzzler3]

First, copy off any files that you can on a separate computer.
Second, format it with the following software: https://members.sdcard.org/downloads/formatter_4/
Third, put the newly formatted card back in the phone and let it "discover" it and tell it to put your photos, videos, etc. on it.
After that you can take the card out (turn off the phone before removal), and copy back the files that you want from where you archived them.
Put the card back in the phone. You should be good to go.

 

[FerdiFerdi]

The same happened a few times with me as well. It is a bug in the o/s. It happens randomly and at times in the middle of the night when the phone (switched on) just lies there. Sometimes it sees the card again after a reboot. Sometimes even after the suggested rescan of the card. Other times I must switch the phone off, take out the card, re-insert it and switch on.
This looks like a bug that is not disappearing. Maybe it will be part of the final o/s.....(I use a Lumia 640)