invoke-rc.d: initscript postgresql, action "stop" failed

 untuk atasi masalah ini, kena tambah line exit 0. maka... edit dengan mana-mana editor

/var/lib/dpkg/info/postgresql*.prerm

dan tambah exit 0 bawah line set -e, seperti di bawah.

#!/bin/sh

set -e

exit 0

VERSION=9.1

. /usr/share/postgresql-common/maintscripts-functions

stop_version $VERSION

if [ "$1" = remove ]; then
    remove_version $VERSION
fi

kemudian cuba upgrade... insyallah proses upgrade akan jalan lancar. ok bye.