Files in the backup created by the app can't be copied off the device

[LinuxOnTheDesktop]

When I use either Linux or Windows to copy a oandbackup folder (the folder containing the backup) from my phone (Lollipop, rooted) to a computer, some items will not copy. The error message (in Linux at least) is something like: could not get file from device. I have the phone connected by USB cable.

One of the problematic items had to do with Chrome; another I did not recognise; after that I told my file manager just to skip all problematic files.

oandbackup version 0.2.13