My trusty old 16GB micro SD card that has been with me through 4 phones is finally full. So I figured no biggie; I'll just buy a new (64GB) card, copy all the files down to my PC (which has no card reader, just USB ports), then up to the new card.

The issue I'm having is that copy step. I have the card in a Note4, connected to a Windows 8 PC via USB. I can see the card, but if I just try to drag-and-drop copy folders to my PC, it invariably ends with a dialog saying:

"A device attached to the system is not functioning".

I'm guessing its on largeish files, as I've noticed .mp4's in particular will just cause Windows explorer to go out to lunch and never come back when I try to copy them individually.

It seems like this ought to be the simplest thing in the world to do. What am I missing?

  • There is this article here which mentioned the cause (faulty HW / filesystem issue) and the resolution (running CHKDSK coupled with some diagnostic/repair tools). It also mentioned additional possible causes which could be an Anti-Virus (Norton there) , IPS, Firewall, etc and suggested disabling them until you're done with your external storage.
    – Firelord
    Commented Apr 29, 2015 at 4:30
  • On a side note, should this question not be on Super User because the issue is from Windows? Though it is not clear yet that Android is completely fine. I guess it suits both sites?
    – Firelord
    Commented Apr 29, 2015 at 4:35
  • @Firelord - I posted here because I've never seen this error before on this Windows system (so it almost certianly has to do with the Android device), and an internet search of the issue showed it appears to be a common problem since Android switched to MTP. However, the usual solution suggested seems to be to force the device into UMS mode, but none of the instructions for doing so work on my Note 4.
    – T.E.D.
    Commented Apr 29, 2015 at 8:24
  • 1
    You might wish to see: How do I switch my Android device's SD card without causing problems? and How do I migrate from one SD card to another one? I specifically recommend: use an sdcard reader (otherwise you will lose some content, especially apps moved to SDCard) – and make sure you catch all "hidden files" (those starting with a .) along.
    – Izzy
    Commented Apr 29, 2015 at 15:02
  • 1
    Not all of them. For example, the .android_secure directory will be inaccessible and usually not exposed, so you couldn't copy it (which would make you lose apps moved to SD). I'm not 100% sure if there are other places where the same applies (though I'm not aware of any). If you've not moved any App2SD, you could of course try: if it doesn't work out, you can always (temporarily) switch back to your old card.
    – Izzy
    Commented Apr 29, 2015 at 15:50

2 Answers 2


Sometimes you can not move files like this using USB. I have faced this issue there are two solutions for this:

1.You can use external card reader and then make copy.

  1. Instead of Drag and Drop open your sd-card window and location where you want to put the files. Then Select folders->copy them and without closing the window paste on the destination.
  • #2 is essentially what I'm doing, so I guess that one's out. I had seen #1 suggested, but I'm not real excited about having to buy yet another special piece of hardware just for this one task. However, it looks like they aren't all that expensive, so perhaps that's the way to go. Still, it seems like this ought to work from Windows directly.
    – T.E.D.
    Commented Apr 29, 2015 at 8:56
  • is it working or not ?
    – Dalvik
    Commented Apr 29, 2015 at 8:58
  • Not. Selecting all the folders in "SD Card", hitting Ctrl-C, then Ctrl-V in a C:\ drive directory is exactly what I was doing initially that gave me this error.
    – T.E.D.
    Commented Apr 29, 2015 at 9:31
  • I don't have any idea about Note4..is their any setting by which you can change the mode of connection..in my phone i have two option mTP mode and Media sharing..try changing this one
    – Dalvik
    Commented Apr 29, 2015 at 9:41

As pointed out in my comment on the question: Copying the SD card while it's mounted in your device might cause you some "data loss". So e.g. the .android_secure directory is "locked down" and won't be exposed to your computer; if you have apps installed on your card, they would "break".

I understand a card reader is not the preferred option for you. So before pointing out possible alternatives, let's take precautions:

if you have apps installed on your card, first move them back to internal storage

There might be other places dealt with similarly – but I am not aware of them. If there seem to be "strange problems" after having finally switched your cards, you can always revert back to your "old card" while figuring out what might have gone wrong.

Now the approaches:

Using ADB via USB

can be quite a universal tool (please check our adb tag-wiki for some details and hints, if you don't know it). Might require a little installation (the tag-wiki has hints on keeping that minimal), but it's worth it – not only for this case!

  • turn on on your device
  • connect it to your PC with the USB cable
  • assuming your device runs Android >= 4.3: at first connect, on your device confirm the "authorization" of your computer
  • on your PC, open a command prompt – and change to the directory you have the ADB executable placed (unless it's in your PATH)
  • adb pull /sdcard \path\to\target now would pull all files from your device's SD card

Using something "wireless"

Multiple choices here:

All in all, to much to elaborate in a single answer here :)

  • 1
    You can also use some apps in Wireless section with USB cable via USB Tethering which enhances the speed (stability too ) since my device seems to have trouble with wireless data transfer. :)
    – Firelord
    Commented Apr 29, 2015 at 17:22
  • 1
    Oh... I forgot the conclusion with the disclaimer: "This answer is far from being complete" :) Thanks, @Firelord – good point!
    – Izzy
    Commented Apr 29, 2015 at 17:37
  • That first option I had come across in my research, but I was unable to figure out how to enable that with a Note 4. I just searched again, and came across this video, which might do the job for me. I'll try it when I get a chance.
    – T.E.D.
    Commented Apr 29, 2015 at 18:06

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