Since this question has not received a reply, maybe I wasn't clear enough in how I asked it...
I'm running Kodi 16.1 on an Android 5.1.1 device. I follow this wiki guide to backup video library to a seagate external USB hard disk.
http://kodi.wiki/view/HOW-TO:Backup_the_video_library
When Kodi gets to the point where it attempts to write the Video library NFO files to the external USB drive a popup appears saying "unable to write to folder". I have full read/write control of the USB hard disk using Android file managers from outside Kodi so I don't understand why I can only read the USB hard disk from the Kodi File Manager or when it attempts to write the backup NFO files of the video library to the drive.
Can someone suggest a way for me to get the video library backed up so I don't lose it if something goes wrong or I want to move the USB HDD to another device and then import the video library to it?
The procedure in the wiki is pretty simple, here is a pertinent excerpt...
Backing up
In Kodi go to Settings -> Videos -> Library and select Export library. Various pop-up windows will show up:
Say "multiple files" when asked how you would like to export.
Say "Yes" when asked about exporting thumbnails and fanart.
Say "Yes" when asked about actor thumbnails. [1]
Say "Yes" when asked if you want to overwrite old files.
Kodi will now export the library, which may take a while depending on your library size and speed of your HTPC and/or network.