This is what I got from synaptic when I tried to install emacs22 and uninstall emacs21 Selecting previously deselected package emacs22. (Reading database ... 139856 files and directories currently installed.) Unpacking emacs22 (from .../emacs22_22.1-0ubuntu5_amd64.deb) ... (Reading database ... 139869 files and directories currently installed.) Removing emacs21 ... emacs-remove emacs21 remove/ecb: purging byte-compiled files for emacs21 remove/cedet-contrib: purging byte-compiled files for emacs21 remove/cogre: purging byte-compiled files for emacs21 remove/jde: purging byte-compiled files for emacs21 remove/semantic: purging byte-compiled files for emacs21 remove/ede: purging byte-compiled files for emacs21 remove/eieio: purging byte-compiled files for emacs21 remove/speedbar: purging byte-compiled files for emacs21 emacsen-common: Handling removal of emacsen flavor emacs21 emacsen-common: purging byte-compiled files for emacs21 remove/elib: Handling removal of emacsen flavor emacs21 remove/cedet-common: purging byte-compiled files for emacs21 Removing emacs21-bin-common ... Removing emacs21-common ... Selecting previously deselected package emacs22-el. (Reading database ... 138751 files and directories currently installed.) Unpacking emacs22-el (from .../emacs22-el_22.1-0ubuntu5_all.deb) ... Setting up emacs22 (22.1-0ubuntu5) ... Setting up eieio (1:1.0pre4-2) ... install/cedet-common: Handling install for emacsen flavor emacs22 Loading 00debian-vars... No /etc/mailname. Reverting to default... Loading /etc/emacs22/site-start.d/35elib-startup.el (source)... Loading /etc/emacs/site-start.d/50cedet-common.el (source)... Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)... Loading debian-ispell... Loading /var/cache/dictionaries-common/emacsen-ispell-default.el (source)... Loading /var/cache/dictionaries-common/emacsen-ispell-dicts.el (source)... Loading /etc/emacs/site-start.d/50eieio.el (source)... Loading /etc/emacs/site-start.d/50jde.el (source)... Loading /etc/emacs/site-start.d/51ede.el (source)... Loading /etc/emacs/site-start.d/51speedbar.el (source)... Loading /etc/emacs/site-start.d/52semantic.el (source)... Loading /etc/emacs/site-start.d/53cedet-contrib.el (source)... Loading /etc/emacs/site-start.d/53cogre.el (source)... Loading /etc/emacs/site-start.d/55ecb.el (source)... "/usr/share/emacs22/site-lisp/cedet-common/" added to `load-path' Error while loading 55ecb Cannot open load file: eieio emacs-package-install: /usr/lib/emacsen-common/packages/install/cedet-common emacs22 emacs22 failed at /usr/lib/emacsen-common/emacs-package-install line 30, line 2. dpkg: error processing eieio (--configure): subprocess post-installation script returned error exit status 255 dpkg: dependency problems prevent configuration of ede: ede depends on eieio (>= 1:1.0pre4-1); however: Package eieio is not configured yet. dpkg: error processing ede (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of semantic: semantic depends on ede; however: Package ede is not configured yet. semantic depends on eieio (>= 1:1.0pre4-1); however: Package eieio is not configured yet. dpkg: error processing semantic (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of jde: jde depends on eieio (>= 1:1.0pre3-6); however: Package eieio is not configured yet. jde depends on semantic (>= 1:1.0pre3-6); however: Package semantic is not configured yet. dpkg: error processing jde (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of cedet-contrib: cedet-contrib depends on semantic (>= 1:1.0pre4-1); however: Package semantic is not configured yet. dpkg: error processing cedet-contrib (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of cogre: cogre depends on semantic (>= 1:1.0pre4-1); however: Package semantic is not configured yet. dpkg: error processing cogre (--configure): dependency problems - leaving unconfigured Setting up emacs22-el (22.1-0ubuntu5) ... Errors were encountered while processing: eieio ede semantic jde cedet-contrib cogre E: Sub-process /usr/bin/dpkg returned an error code (1) A package failed to install. Trying to recover: Setting up eieio (1:1.0pre4-2) ... install/cedet-common: Handling install for emacsen flavor emacs22 Loading 00debian-vars... No /etc/mailname. Reverting to default... Loading /etc/emacs22/site-start.d/35elib-startup.el (source)... Loading /etc/emacs/site-start.d/50cedet-common.el (source)... Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)... Loading debian-ispell... Loading /var/cache/dictionaries-common/emacsen-ispell-default.el (source)... Loading /var/cache/dictionaries-common/emacsen-ispell-dicts.el (source)... Loading /etc/emacs/site-start.d/50eieio.el (source)... Loading /etc/emacs/site-start.d/50jde.el (source)... Loading /etc/emacs/site-start.d/51ede.el (source)... Loading /etc/emacs/site-start.d/51speedbar.el (source)... Loading /etc/emacs/site-start.d/52semantic.el (source)... Loading /etc/emacs/site-start.d/53cedet-contrib.el (source)... Loading /etc/emacs/site-start.d/53cogre.el (source)... Loading /etc/emacs/site-start.d/55ecb.el (source)... "/usr/share/emacs22/site-lisp/cedet-common/" added to `load-path' Error while loading 55ecb Cannot open load file: eieio emacs-package-install: /usr/lib/emacsen-common/packages/install/cedet-common emacs22 emacs22 failed at /usr/lib/emacsen-common/emacs-package-install line 30, line 2. dpkg: error processing eieio (--configure): subprocess post-installation script returned error exit status 255 dpkg: dependency problems prevent configuration of ede: ede depends on eieio (>= 1:1.0pre4-1); however: Package eieio is not configured yet. dpkg: error processing ede (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of jde: jde depends on eieio (>= 1:1.0pre3-6); however: Package eieio is not configured yet. dpkg: error processing jde (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of semantic: semantic depends on ede; however: Package ede is not configured yet. semantic depends on eieio (>= 1:1.0pre4-1); however: Package eieio is not configured yet. dpkg: error processing semantic (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of cedet-contrib: cedet-contrib depends on semantic (>= 1:1.0pre4-1); however: Package semantic is not configured yet. dpkg: error processing cedet-contrib (--configure): dependency problems - leaving unconfigured dpkg: dependency problems prevent configuration of cogre: cogre depends on semantic (>= 1:1.0pre4-1); however: Package semantic is not configured yet. dpkg: error processing cogre (--configure): dependency problems - leaving unconfigured