failed to start child: Phoenix.PubSub.PG2

[qg-hs]

I have encountered a problem
(Mix) Could not start application ret: Ret.Application.start(:normal, []) returned an error: shutdown: failed to start child: RetWeb.Endpoint
** (EXIT) shutdown: failed to start child: Phoenix.PubSub.PG2
** (EXIT) shutdown: failed to start child: Phoenix.PubSub.PG2Server
** (EXIT) an exception was raised:
** (UndefinedFunctionError) function :pg2.create/1 is undefined or private
(kernel 9.0.2) :pg2.create({:phx, Ret.PubSub})
(phoenix_pubsub 1.1.2) lib/phoenix/pubsub/pg2_server.ex:43: Phoenix.PubSub.PG2Server.init/1
(stdlib 5.0.2) gen_server.erl:962: :gen_server.init_it/2
(stdlib 5.0.2) gen_server.erl:917: :gen_server.init_it/6
(stdlib 5.0.2) proc_lib.erl:241: :proc_lib.init_p_do_apply/3