Recently i have noticed a strange issue with my Nokia asha 501 when i try to copy files from ubuntu the files becomes corrupted and unreadable.this is a Linux specific issue but works fine in windows.after lots of research i have found a solution (also works with other nokia asha models also).
Run this command in terminal: lsusb | grep ‘Nokia’
copy the line starts with “ID:4253333333”
open terminal and run this command: sudo gedit /etc/modprobe.d/usb-storage-devices.conf
add the following content to gedit: options usb-storage quirks=xxxx:xxxx:m
Now replace the XXXX:XXXXX with the id you copied earlier (eg : options usb-storage quirks=0421:068:m)
Save the file and close gedit.
Disconnect the phone from usb cable
Restart the pc or run this command in terminal sudo rmmod usb-storage
Connect the device in mass storage mode again , now you can copy files without any issue .