Problem:

lmsplus=> SELECT current_setting('lms.current_user', '0', false);
ERROR:  function current_setting(unknown, unknown, boolean) does not exist
LINE 1: SELECT current_setting('lms.current_user', '0', false);
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

Rozwiązanie:

SELECT set_config('lms.current_user', '0', false);
SELECT current_setting('lms.current_user', false);