When upgrading to Ubuntu 14.04 from Ubuntu 12.04 I am getting the following error:
W:Failed to fetch http://deb.opera.com/opera-beta/dists/stable/Release
Unable to find expected entry 'non-free/source/Sources' in Release
file (Wrong sources.list entry or malformed file) , E:Some index files
failed to download. They have been ignored, or old ones used instead.