I had the same problem after the update to 2.5.0
I've been trying to discover if there was some driver issue that would cause the problems I have been having in copying large files to a Kobo Glo since I updated to 2.5.0. ( see
https://www.mobileread.com/forums/sho...&postcount=212 and subsequent posts).
Expanding both the 2.4 and 2.5 update packages I found the following files that looked as if they might have some bearing on the matter :
\drivers\ntx508\usb\gadget\g_file_storage.ko
and
\drivers\freescale\usb\gadget\g_file_storage.ko
Clearly the two are variants for different processors. I've come across the reference to Linux File-Backed Storage Gadget on my Hanlin V3s which is how the exported USB drives appear there and this is why I suspect that these drivers on the Glo fulfil a similar function (there is some info about the Mass Storage Gadget at
http://www.linux-usb.org/gadget/ ). Although there are other files in the same folders when I compare files the one above is the only ones which is different between the 2.4 and the 2.5 releases.
The problem re-occurred with 2.5.1.
I have now reverted to 2.4.0 and to date I haven't had a problem (but I haven't been doing any intensive coying so this isn't conclusive).
If you read through the thread mentioned above you will see that the problem is not Calibre related - I have hit copying problems even when Calibre is not active.
Reading the info on the Mass Storage gadget it does mention circumstances where the USB connection can become unstable.
To date I have not been able to reliably reproduce the error which occurs randomly with periods of being able to copy large files then bombing out on a small one.
I thought I was the only one with this problem but it looks like I might not be.
BobC