SD card not recognized/won't mount

[Ed Simons]

Recently developed a problem with the phone not recognizing my SanDisk 64Gb micro SDXC card. The card had been working fine for 8+ weeks then errors started creeping in when I plugged it into my PC. Nothing major, just minor oddities. Somewhere in this time frame I had downloaded the App2SD app to try to move some of the apps to the SD card. Never had any success with this app moving anything I wanted to move. Today the phone would not recognize the SD card apps. I switched back to my older 32Gb card - no problems. Used an external USB reeader on the PC to back up the 64Gb card and did a reformat then copied the data back to it. Put it back in the phone, same problem - can't mount it, card not recognized. Any suggestions?

[PS: the phone is a stock BOOST Mobile version of the HTC EVO Design 4G]

 

[AndroidProf]

Recently developed a problem with the phone not recognizing my SanDisk 64Gb micro SDXC card. The card had been working fine for 8+ weeks then errors started creeping in when I plugged it into my PC. Nothing major, just minor oddities. Somewhere in this time frame I had downloaded the App2SD app to try to move some of the apps to the SD card. Never had any success with this app moving anything I wanted to move. Today the phone would not recognize the SD card apps. I switched back to my older 32Gb card - no problems. Used an external USB reeader on the PC to back up the 64Gb card and did a reformat then copied the data back to it. Put it back in the phone, same problem - can't mount it, card not recognized. Any suggestions?

[PS: the phone is a stock BOOST Mobile version of the HTC EVO Design 4G]

Its a good thing that you backed up your data and reformatted it. I am curious whether you have tried any other 64GB SD on your phone to know whether its the phone or the SD card that won't work. The fact that it works on a PC doesn't necessarily mean it will work on your phone. Can you try your SD card on another device, if it works fine then the problem lies with your phone. But if it doesn't work on another phone, then the problem is your SD card and that would mean replacing it. You could also try reading the card using a USB cable while its still inside the phone. Also since you have formatted the card, can you try switching off the phone then switching it back on then insert the SD card. I hope one of these works...

 

[Ed Simons]

Yes I could find a friend that has a smart phone (or similar device) that supports a 64Gb SD card to try it out. As for trying to read the card directly after connecting with a USB cable - do you mean with a PC or am I missing something where I can connect with some other type device that has a display to inspect the SD card? My thinking is this, on the SD card reader at the kernel level on the HTC EVO Design there is a bit mask that has gotten set to a bad value for reading 64Gb cards (they are not officially supported)- but that is only a guess. Since I have reverted to back to a 32Gb card it's not too much problem for now, but I am a music junkie with 3 Gb left of the 32 Gb. I also tried running chkdsk thru a sd card reader on a PC w/Win 7 but "it never came back" with any response, hmm.

Update: I was able to run chkdsk (via a PC running Win 7) on the SD card thru a card reader and it did not find any errors with the SD card. So I am thinking it is a problem with the card reader on the HTC. But again the HTC ran the 64Gb card just fine for several weeks and is now running the 32Gb card w/o any problems. Any chance it was the App2SD Android app that initiated this problem. Note: I uninstalled that App once the problems appeared w/the 64Gb card.

Update 2: The actual Android App was AppMgr III (App 2 SD).