sudo apt-get update i get the following error message:
... Ign http://packages.linuxmint.com rebecca/upstream Translation-en_US Ign http://packages.linuxmint.com rebecca/upstream Translation-en Fetched 3.039 kB in 36s (83,1 kB/s) N: Ignoring file 'getdeb.list.bck' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension W: Failed to fetch http://archive.getdeb.net/ubuntu/dists/rebecca-getdeb/apps/binary-amd64/Packages 404 Not Found [IP: 184.108.40.206 80] W: Failed to fetch http://archive.getdeb.net/ubuntu/dists/rebecca-getdeb/apps/binary-i386/Packages 404 Not Found [IP: 220.127.116.11 80] E: Some index files failed to download. They have been ignored, or old ones used instead.
Moreover, finding out the folder
/etc/apt/sources.list.d I cannnot neither delete the file that create problem or modify that; I can only open it to see the text file content.
Could someone suggest a solution and provide some references about?