PostgreSQL - relation "pg_stat_statements" does not exist

What I did:
select * from pg_stat_statements;
-- and pg_stat_statements is enabled (if not - check here)

Error message:
ERROR:  pg_stat_statements must be loaded via shared_preload_libraries

Cause:
pg_stat_statements is not set in postgresql.conf.
It probably looks like:
#shared_preload_libraries = '' # (change requires restart)
or with other libraries.

Solution:
1. Set pg_stat_statements in postgresql.conf; adding:

shared_preload_libraries = 'pg_stat_statements'

pg_stat_statements.max = 10000
pg_stat_statements.track = all

2. Restart PostgreSQL service

Check it:
SHOW shared_preload_libraries;