Wednesday, 13 March 2013

The Dreaded "Server (IO) Error"

Occasionally, there are times when trying to upload a file using WiFi File Explorer PRO that the file won't upload.  If your eyes are in the right place of the screen (the upload section, on the box representing the file to be uploaded) and you are quick enough (before the page refreshes) you may just see the words "Server (IO) Error" and wonder just what on earth that means.

Well, it's a bit of a generic error and as you can see, not very descriptive on its own.  But luckily it only actually occurs in a handful of situations, and after reading descriptions of those below, you should be able to quickly work out which one refers to what you are doing.

So here are the ways in which you can cause the "Server (IO) Error":

1. You are attempting to upload to a read-only area of storage.  Remember that not everywhere you can view on your Android device's storage can be written to (even if you are rooted, as WiFi File Explorer does not support root operations).  If you are unsure of what areas are read-only or not, then I suggest searching the internet for information relating to your device as it can vary greatly.  Also, remember some SD cards have a read-only physical slider on the actual SD card itself and this may have been accidentally (or purposefully) switched on.

2. Your storage is full, or, you would fill it if you upload that particular file.  Not much to explain here other than to check how much storage you are using and delete as necessary if that is the issue.

3. You are uploading a file bigger than 4GB.  I am afraid that is the limit that the Flash plugin used to upload the files is able to handle (perhaps linked to the limit of a FAT32 based file system).

4. Your storage is not correctly mounted.  This doesn't just mean physically mounted correctly into the device, but also logically by the Android OS.  Switching the device off and back on again should ensure it is logically mounted again correctly, but it could also be another app doing something strange to it.

The only other time someone has reported this error, but unrelated to the scenarios above, was to do with his particular Flash installation.  He could get it working on one PC, but not the other.  However, this is purely anecdotal and I can't confirm the validity of his claim that it was to do with the Flash install.  It may be worth bearing in mind though if you can't link the error to any of the descriptions above, so perhaps try updating to the latest version of Flash.

And as always, if you still have trouble after reading this, then please feel free to email me for personal support.

Update: After updating your device to Android 4.4 (KitKat), you may find that you are no longer able to perform some functionality on the external SD card that you were previously.  This is because some device manufacturers have not changed the default behavior of Android 4.4 which is to not allow write operations to the external SD card (see point 1 above).  This "bug" is particularly evident on Samsung devices and I have no information on whether Samsung plan to address it in future Android updates or not.


  1. WiFi file explorer is the first time to be able and then some, trancfer files from android to PC without using a cable

  2. This app has worked flawlessly for several years (I bought the Pro version for me and my wife) and it is installed on all my mobile devices, but .... I recently changed phones (Galaxy S3 to Note 3). My browser connects fine, but when I try to do anything (delete, upload) I receive the "server I/O error". The file is only 812KB and the external SD card has 55GB free. I am uploading to a directory I created in the external SD card root and that I have used before. I can put the file in that location using a cable. I removed your app and intstaIled anew and I still get the error. I disabled the antivirus that comes pre-installed (so I can't remove it) and I still get the error. Any suggestions?

    1. Please see the update to the post above.

    2. Thank you for the update. The limitations imposed on the device by Android and/or manufacturers is insane. Ridiculous. If I want to limit writes to my SD card I can set the physical write protect. Just harms people like me and causes support headaches for fine developers like you.

      Keep up the great work and thank you for your excellent product.

    3. you can fix it, saving to the internal memory.

  3. Please enable root explorer mode! I have root rights on my phone and want to access all directories with wifi file explorer pro...

  4. if I knew I would have problems with the update for KITKAT not have done.
    I now have an APP that does nothing.

    there is no solution to the same error?

    my device is Samsung Galaxy GT-I9200

  5. You can fix this problem if you root your phone. You need to edit platform.xml as described here:

  6. I read that Lollipop is more generous when it comes to external storage permissions. Does that mean that WiFi File Explorer is now able to upload files with no problems no matter the destination?

  7. I think I know how to solve this problem now. I will share this post on my website. Thanks!

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