If one tries to install an unsigned extension in Firefox ESR 60 (after allowing it in the profile) it will complain about the extension being damaged (NOT unsigned) if there's no "id" in it. So I added an id--it works fine now. Tested on Linux using: unzip "dissenter_extension-0.1.10-fx.xpi", edit "manifest.json", zip the whole thing again and install the resulting xpi in "about:addons" (top right corner gear menu). You might still want to adapt the id to what you usually use - but it doesn't work without any id.
If one tries to install an unsigned extension in Firefox ESR 60 (after allowing it in the profile) it will complain about the extension being damaged (NOT unsigned) if there's no "id" in it. So I added an id--it works fine now. Tested on Linux using: unzip "dissenter_extension-0.1.10-fx.xpi", edit "manifest.json", zip the whole thing again and install the resulting xpi in "about:addons" (top right corner gear menu). You might still want to adapt the id to what you usually use - but it doesn't work without any id.