I followed the instructions for upgrading phoenix 1.4 to 1.5.0-rc.0 but when I run mix phx.server. I get the following error.

** (Mix) Could not start application patchtrace: Patchtrace.Application.start(:normal, []) 
returned an error: shutdown: failed to start child: PatchtraceWeb.Endpoint
** (EXIT) an exception was raised:
    ** (UndefinedFunctionError) function Phoenix.Socket.__child_spec__/2 is undefined or 
private
        (phoenix 1.5.0-rc.0) Phoenix.Socket.__child_spec__(Phoenix.LiveReloader.Socket, 
[endpoint: PatchtraceWeb.Endpoint])
        (elixir 1.10.1) lib/enum.ex:1396: Enum."-map/2-lists^map/1-0-"/2
        (phoenix 1.5.0-rc.0) lib/phoenix/endpoint/supervisor.ex:105: 
Phoenix.Endpoint.Supervisor.init/1
        (stdlib 3.11.2) supervisor.erl:295: :supervisor.init/1
        (stdlib 3.11.2) gen_server.erl:374: :gen_server.init_it/2
        (stdlib 3.11.2) gen_server.erl:342: :gen_server.init_it/6
        (stdlib 3.11.2) proc_lib.erl:249: :proc_lib.init_p_do_apply/3

Any ideas