An microSD Card that keeps unmounting and disconnecting from HTC 10 is an issue that may root on the phone or from the SD card itself. You can find out what cause the problem in the first place and solve it.
You may have problem with the SD card in your HTC 10, where it keeps disconnecting or unmounting from time to time. If you keep getting pop up message that inform you about this issue, then you need to check whether the problem lay on the SD card or on your phone.
SD Card Unmounting Issue on HTC 10
You can try to test the card in another device to see whether the same problem still happens or not. If it’s not, then there is nothing wrong with the card.
You also may want to try using another SD card. If the problem persists, then there could be some underlying issue with the phone. But if it’s not, then perhaps the previous card is the one that your phone have problem with.
Restart or reboot the phone may help to solve this problem temporarily. Press and hold Power button and then tap Restart option to restart the phone. If this method doesn’t work, press and hold Power button and Volume Down button for several seconds, where it will force the phone to reboot.
Try to remove the SD card for a while and then return it back again. You can do this by hold the Power button and tap Turn Off option. It will turn off the phone so you can release SD card safely before putting it back on, where you can turn on the phone and give it a try and see whether the problem still persist or not.
Last thing to do is formatting the microSD card on your HTC 10. Before you do this, make sure that you already back up the entire content of SD card in your computer. After that, you can start to format the card from Settings > Storage and then tap the gear icon next to SD card and choose Format.