I just installed the new version of Firefox (59.0+build5-0ubuntu0.16.04.1) and I get this when I start it (translated from French):
Error analyzing XML: entity not defined Location: chrome://browser/content/browser.xul Line number 343, column 5: <key id="key_quitApplication" key="&quitApplicationCmd.key;" ----^
I have no button and no menu. I can do nothing in the browser. I tried to uninstall it and reinstall. Always the same error.