I bought a Samsung Galaxy Grand Prime earlier this year. It has Android version 5.0.2 on it. I installed a 64gb SD card for extra memory. Phone worked great and I was able to transfer (upload) files from my PC to it via USB connection, no problem - at least for the 1st month I had it. Recently, it will not accept any uploads (not to the phone or the mounted SD card). The progress bar just hangs at either 25% completion or 100% completion indefinitely and it won't ever complete the transfer. The only way I can transfer files to this phone is via email or Bluetooth connection. So what happened? The first month I had it was able to transfer files to it, no problem. I have always been able to download files from it to my PC (via USB cable), and still can despite the fact I can no longer upload files to it. I tried Samsung Kies3 software and it is able to do a backup but it can't upload files to the phone either.