Upgrade to postgres 10 - Postmaster not getting shutdown

[Debraj Manna <subharaj.manna@xxxxxxxxx>]

Hi 

I am trying to upgrade to postgres 10 from 9.5.4. On doing the compatibility check I am getting the below error. 

ubuntu@vrni-platform-release:/tmp$ sudo service postgresql stop

 * Stopping PostgreSQL 10 database server                                                                                                                                                            [ OK ]

 * Stopping PostgreSQL 9.5 database server                                                                                                                                                           [ OK ]

ubuntu@vrni-platform-release:/tmp$ sudo -H -u postgres /usr/lib/postgresql/10/bin/pg_upgrade -b /usr/lib/postgresql/9.5/bin -B /usr/lib/postgresql/10/bin -d /var/lib/postgresql/data/postgresql0 -D /var/lib/postgresql/10/data/postgresql0 -o ' -c config_file=/etc/postgresql/9.5/main/postgresql.conf' -O ' -c config_file=/etc/postgresql/10/main/postgresql.conf' --check -k

There seems to be a postmaster servicing the new cluster.

Please shutdown that postmaster and try again.

Failure, exiting

Can some one let me know what is going wrong here and how can I get around this?

Thanks,

Debraj