will not upgrade from 14.04 LTS to 16.04

[Michael Crider]

Ran "sudo do-release-upgrade -d" on Ubuntu Server, was told
Could not calculate the upgrade

Problem was solved by first manually removing postgresql-9.1 and related packages from previous upgrade, leaving postgresql-9.3 packages in place, then repeating the upgrade.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 3.13.0-88.135-generic 3.13.11-ckt39
Uname: Linux 3.13.0-88-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
CrashDB: ubuntu
CurrentDmesg.txt:
 [ 9.237260] postgres (963): /proc/963/oom_adj is deprecated, please use /proc/963/oom_score_adj instead.
 [ 16.486804] init: plymouth-upstart-bridge main process ended, respawning
 [ 21.917193] random: nonblocking pool is initialized
Date: Sun Jun 19 04:58:06 2016
InstallationDate: Installed on 2012-08-21 (1397 days ago)
InstallationMedia: Ubuntu-Server 12.04 LTS "Precise Pangolin" - Release amd64 (20120424.1)
PackageArchitecture: all
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-06-19 (0 days ago)