[99s-extend] Cowboy + SSL

[e at bestmx.net]

Hello.

i still have a problem with SSL.
as soon as i change cowboy:start_http call to cowboy:start_https
my release refuses to stop (when requested)
and when i revert to "http" it starts and stops normally.

i am sure it is the only difference: start_http vs. start_https

i am using relx with default settings as it was provided by cowboy
(Erlang R17, System: Debian "testing")

here is my_app.erl:

start(_Type, _Args) ->
   Dispatch =
   cowboy_router:compile([{'_', [{"/start", ws_handler, []}]}]),

   cowboy:start_https( https, 100, [ {port, 8765}
   , {cacertfile, ?Dir ++ "/ssl/cowboy-ca.crt"}
   , {certfile, ?Dir ++ "/ssl/server.crt"}
   , {keyfile, ?Dir ++ "/ssl/server.key"} ]
   , [{env, [{dispatch, Dispatch}]}]),

   online37_sup:start_link().

stop(_State) -> ok.


once i call:
release/bin/my_release stop

the erlang.log repeats hundreds of:

=ERROR REPORT==== 19-Jan-2015::20:06:02 ===
Error in process <0.234.0> on node 'online37 at 127.0.0.1' with exit value: 
{{case_clause,{error,closed}},[{ranch_acceptor,loop,3,[{file,"src/ranch_acceptor.erl"},{line,28}]}]}


what could it be?
any misconfiguration of my system (regarding ssl support)?
what exactly does ranch expect from me?