Starting with GitLab 13.0, Puma will be the default web server used in
omnibus-gitlab based installations. This will be the case for both fresh
installations as well as upgrades, unless users have explicitly disabled Puma
and enabled Unicorn. Users who have
Unicorn configuration are recommended to refer to the docs on how to convert them to Puma ones.
To upgrade to GitLab 13.0 or later, users must be already running PostgreSQL 11. PostgreSQL 9.6 and 10 have been removed from the package. Follow the documentation on how to upgrade the packaged PostgreSQL server to required version.