Copying files from a MicroSD card to PC fails

On an Android phone the 64GB MicroSD storage expansion card was nearly full. I replaced it with a 128GB card. I plugged the old 64GB card in my Windows PC and started copying the photos and videos from it to my hard disk. There was nearly 64GB of data so I left it copying... Upon my return I found it had stopped after only copying only a few files. There was a semaphore error.

Maybe there was a corrupt file? The MicroSD card could be corrupt or faulty?

I tried the file copy again but this time I used the Robocopy command line, it is more robust than Explorer and I felt perhaps it would do a better job. Robocopy also stopped after copying just a few files. It was as thorough the SD card was no longer recognised by my PC.

Robocopy ERROR 121 (0x00000079)
The semaphore timeout period has expired.

I tried a different USB port
I tried a different SD card reader
No success.

I ran the Robocopy command, when it got stuck I removed the SD card physically from the computer, then plugged it back in. It would copy more files... Until getting stuck again. I successfully used this method to copy a large number of files but with hundreds of files this was not a viable solution.

I noticed that mostly smaller files were being copied more often than larger ones. Video files of 100MB just got stuck.

For the video files over 50MB I used 7-Zip to create a compressed file with volumes. I ended up with lots of 1.44MB files. I managed to copy these smaller files to the C: drive and extract the video file. I continued with this for a time, I was mostly successful. But this was slow and the semaphore error came up again. 

Solution
I did a lot of searching on the web, I came across an application called Backupper. I tried this to synchronise a folder on the old MicroSD card to my C: drive. This worked! It does take a long time and it is quirky software because it has a percentage complete that goes steadily to 76% and appears to get stuck there. But it is still working, if you open Explorer to the destination folder you will see new files appear. Be patient though, in my case I left it running all day.

In the above screen shot you'll see that it couldn't read a file. In this case you'll just have to accept that, because it can't work miracles, some files might be corrupt/damaged. I did recover most of the files though.


Conclusion
If you have the semaphore error do not despair. Try Backupper, it's worth a go.

Of course it does raise a question over the reliability of MicroSD cards. My feeling is that when you have used a card extensively and almost filled it with so many files, the possibility of a failure like this grows. Contemplate replacing your micro SD card every few years and of course back up. Google Photos backup is free therefore at least for JPGs you can safeguard them. For videos maybe copy them off your phone periodically?

I hope this was helpful. Many thanks to Backupper.
https://www.ubackup.com/download.html

Disclaimer

I am not guaranteeing anything here. This is just my experience! Good luck.

Related
You might also be interested in the following recent article I wrote about a problem I found with MicroSD cards. This is more related to the speed of the card and which one to purchase.
https://mgxp.blogspot.com/2019/12/which-microsd-card-should-i-use-in-my.html

Which MicroSD card should I use in my Dell Inspiron 13 5391?

Recently I bought a shiny new computer, the Dell Inspiron 13 5391. It's a high-spec but reasonably priced laptop (as of November 2019), I'm very happy with it.

The 5391 has a MicroSD card slot. I wanted to use a MicroSD card for backup. I bought a SanDisk Ultra, U1, (10). I have used these cards before, they are inexpensive and a reasonable speed. As I was only backing up files to it, I felt I didn't need more. I plugged this MicroSD card into my 5391 and it appeared as a drive, all appeared normal at first...


Problem
However, when I tried to use it, my computer, in general slowed down. Copying files was like watching a video in slow motion. I tried to set up Windows File History, it gave the error "Could not enable File History". Formatting the card was taking minutes and eventually I had to reboot my PC. I tried the same card in another computer and it read it without problem. I tried the same card in an Android smartphone, it worked fine. I formatted it there. I put it back in my 5391, still the same problem...

I recommend a fast U3 MicroSD card for use with the Dell Inspiron 5391

Solution
I tried another, faster MicroSD card that I already owned. The Toshiba Exceria U3 is a faster card (U3 as opposed to the slower U1) and when I put it into my 5391, it works perfectly! I'm using File History on it without any trouble.


Conclusion
Let's be clear, I am not saying SanDisk don't make good MicroSD cards. I believe my Dell Inspiron 5391 (purchased from Dell Europe) requires a faster MicroSD card. I can tell you for sure that the Toshiba Exceria U3 128GB works. It is very likely that a similar U3 card by SanDisk would also work too. The SanDisk card that I bought, I am currently using it in my Android smartphone without any trouble.

I hope that has helped others who purchase Dell Inspiron 5391 (I have the 13" European model). Pay a bit extra and get a faster card, it's more likely to work!


Reference

• U3 = 30MB/sec transfer
• U1 =10MB/sec transfer

The following link explains more about SD cards and their speed ratings:
https://en.wikipedia.org/wiki/SD_card


Disclaimer
Everything I've written here is to the best of my knowledge and experience only. I have not made any extensive tests. I've written this article to help others.

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