I'm trying to upgrade PostgreSQL on Ubuntu Server from 9.6 to 10. This is the first time I'm doing this. The server doesn't contain any useful data yet but I want to make sure I can do this properly next time.

I followed the instructions in the manual. Here's what I did:

  • Installed the new packages for version 10
  • Stopped both versions on the server
  • Ran the pg_upgrade script:

    sudo -u postgres /usr/lib/postgresql/10/bin/pg_upgrade -b /usr/lib/postgresql/9.6/bin -B /usr/lib/postgresql/10/bin -d /var/lib/postgresql/9.6/main/ -D /var/lib/postgresql/10/main/

This is the console output:

Performing Consistency Checks
Checking cluster versions                                   ok

Consult the last few lines of "pg_upgrade_server.log" for
the probable cause of the failure.

connection to database failed: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/lib/postgresql/.s.PGSQL.50432"?

could not connect to source postmaster started with the command:
"/usr/lib/postgresql/9.6/bin/pg_ctl" -w -l "pg_upgrade_server.log" -D "/var/lib/postgresql/9.6/main/" -o "-p 50432 -b  -c listen_addresses='' -c unix_socket_permissions=0700 -c unix_socket_directories='/var/lib/postgresql'" start
Failure, exiting

This is the contents of pg_upgrade_server.log:

command: "/usr/lib/postgresql/9.6/bin/pg_ctl" -w -l "pg_upgrade_server.log" -D "/var/lib/postgresql/9.6/main/" -o "-p 50432 -b  -c listen_addresses='' -c unix_socket_permissions=0700 -c unix_socket_directories='/var/lib/postgresql'" start >> "pg_upgrade_server.log" 2>&1
waiting for server to start....postgres: could not access the server configuration file "/var/lib/postgresql/9.6/main/postgresql.conf": No such file or directory
 stopped waiting
pg_ctl: could not start server
Examine the log output.

I'm totally confused now. What should I do?


2 Answers 2


You know what they say about the word assume

I assumed the config dir and data dir was the same. Answer 1:

Change your command to this and it will work.

sudo -u postgres /usr/lib/postgresql/10/bin/pg_upgrade \
-b /usr/lib/postgresql/9.6/bin -B /usr/lib/postgresql/10/bin \
-d /var/lib/postgresql/9.6/main/ -D /var/lib/postgresql/10/main/
-o '-c config_file=/etc/postgresql/9.6/main/postgresql.conf' \
-O '-c config_file=/etc/postgresql/10/main/postgresql.conf'

we can provide the special config file location as an option

Also, I believe you have identified a default install issue or the documentation needs to be updated

The default install should create the config files in the datadir

Answer 2:

Since this is play, try this too:

sudo -u postgres pg_dropcluster 10 main
sudo -u postgres pg_upgradecluster 9.6 main

Keeping this, since it might help someone else.

The empty databases seem to have not been created yet. Or are in a different directory. That's why postgresql.conf is not found in the error message.

ls -l /var/lib/postgresql/9.6/main/postgresql.conf /var/lib/postgresql/10/main/postgresql.conf

should show two files.

The equivalent initdb command for both versions should be run

pg_ctl -D /var/lib/postgresql/9.6/main initdb

pg_ctl -D /var/lib/postgresql/10/main initdb
  • 1
    They're in different directories: /etc/postgresql/10/main/postgresql.conf for the config and /var/lib/postgresql/10/main/ for the data. That's how Postgres' original package for Ubuntu/Debian does it. Is that packaging incompatible with Postgres' own tools?
    – ygoe
    Commented Nov 10, 2017 at 8:03
  • 2
    So I was wrong to say that -d & -D are location of where the data and config files are. It's actually the config directory. Thanks - I learnt something today and the documentation needs to be updated too
    – amacvar
    Commented Nov 10, 2017 at 17:07
  • 1
    Thanks, it worked with the config directory. The documentation seems wrong here.
    – ygoe
    Commented Nov 10, 2017 at 22:01
  • 10
    Thanks, I made some progress following this answer. However both the old and new options parameters should have -c before the config_file so -o '-c config_file=/path/to/postgresql.conf'. Also, I think the 3rd line in your Answer 1 is missing a backslash.
    – hsebastian
    Commented Jan 30, 2018 at 23:04
  • 1
    On Ubuntu 20.04, doing an upgrade from postgres 9.5 to 12, the comment by @hsebastian about adding -c was crucial.
    – dthor
    Commented Dec 17, 2020 at 16:58

I've recently did DB upgrade from 8.4 to 11, on same machine, using pg_upgrade.

Issue was that in 8.4 instance, configuration file - postgresql.conf, unix_socket_directory parameter was empty.

Changes as below, in 8.4 postgresql.conf:

unix_socket_directory = '/var/run/postgresql'

solved the issue.

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