I get this error message when trying to become root in terminal or when trying to open package manager or update manager. The message is also displayed in the top task bar next to the time.
(E: Type 'sudo' is not known on line 56 in source list /etc/apt/sources.list
E: The list of sources could not be read.
Go to the repository dialog to correct the problem.
E: _cache->open() failed, please report.)
I'm not sure what I did last before that error message started to appear. I added the source.list file I just added the .txt extension to upload it in case that helps find a solution. Thanks