I uninstalled the locally installed version of XML::SAX (re https://bugs.launchpad.net/bugs/365384), after which upgrading succeeded this time. It seems then that the bug mentioned above was causing this error.
I uninstalled the locally installed version of XML::SAX (re https:/ /bugs.launchpad .net/bugs/ 365384), after which upgrading succeeded this time. It seems then that the bug mentioned above was causing this error.