Sometimes the little things can cause a big headache
The Android 4.3 update for your shiny new Galaxy S4 Google Play editionphone has a minor issue that is frustrating more than a few users. Most apps can no longer write anything to the SD card, and instead just give you an error when you try doing it.
It's one of those little things that can cause a lot of headache. The technical reasons are a group ID issue, and applications aren't given permission to access the external storage for writing because they aren't in the right group. It's a Unix thing, and if you don't understand it all you're not alone — just know that it's an easy fix in a number of different ways, and hopefully it gets fixed soon. If you do understand, we'll cover it a little more later in this post.
While we're waiting for a permanent fix, the good news is that you can copy files to the external SD card by hand, as long as you use ES File Explorer to do so. Either through magic, or crafty developing, ES File Explorer is a member of the correct group to both read and write to the SD card. There may be other apps that can do the same, but we'll recommend this one because we've tested it ourselves and know it works. Grab it at from the Google Play download link above. If you're the type who likes to dig into things and break fix them yourself, or just a little nerdy and curious, head past the break.
As mentioned before, there's a bug where applications aren't a member of the correct group to write to the SD card. Maybe Google and Samsung meant it to be this way and application developers will need to adjust, or maybe it got overlooked, but for now you can fix it yourself if you're rooted and confident.
See the image above? That's the /system/etc/permissions/platform.xml file. Line 71, the highlighted one, is what you need to add to allow apps to write to the SD card. You can edit this file right on your phone, or pull it to your computer for editing then push it back. Either way, you need to be rooted to fix it. All you are doing is telling the system that the media_rw group is also allowed to write to the SD card. It's very likely this is how it was supposed to work, but it just got overlooked in the rush to get 4.3 out the door.
If you don't want to root your phone — that was one of the big draws of the Google Play edition devices in the first place — stick with ES File Explorer for now. Hopefully this gets sorted soon!