Hi, I am having difficulties updating software. This is due I believe to a repository being invalid. when I type "sudo apt update" in the terminal I get the following error, E: The repository 'http://ppa.launchpad.net/alexmurray/indicator-sensors/ubuntu bionic Release' does not have a Release file. This seems to stop anything at all from updating. I have navigated to /etc apt sources.list.d but the bad repository is locked so I cannot delete it. Is it possible to log in as root and delete the repository and is this a hammer to crack a walnut approach. Alternatively I believe Ubuntu has an editable repository list, does such a thing exist for elementary and if so where is it located please. Any help would be much appreciated please. SOLVED IT MYSELF, I right clicked on the files icon in the dock and selected "New window as administrator". This allowed me to delete the bad repository and now "sudo apt update && sudo apt upgrade" works fine"
