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.
Best Answer
You probably had a ppa before for installing Opera? If that is the case then it's likely that that ppa has not yet been updated for 14.04.
You can remove the offending item from your sources list by pressing the Super key and getting up 'Software & Updates', going through to the 'Other Software' tab and unticking the opera entry. (This will get rid of the error).
To actually get Opera back, I would have a look on their site, or use the instructions here:
http://www.enqlu.com/2014/04/how-to-install-opera-browser-on-ubuntu.html