Strange error in Phoenix logs

I am getting following error in the phoenix webapp, I am developing. This is a simple app with few models and a page, where all models create form is added in a multi-tabbed form.

I am getting following error in the logs, However at browser's end things are working fine. From the logs also I am not able to understand what is wrong and how to debug this.

[error] #PID<0.1603.0> running MyApp.Endpoint terminated
Server: localhost:4000 (http)
Request: GET /
** (exit) an exception was raised:
    ** (Plug.Conn.AlreadySentError) the response was already sent
        (plug) lib/plug/conn.ex:428: Plug.Conn.resp/3
        (plug) lib/plug/conn.ex:415: Plug.Conn.send_resp/3
        (my_app) web/controllers/personal_info_controller.ex:1: MyApp.PersonalInfoController.phoenix_controller_pipeline/2
        (my_app) lib/phoenix/router.ex:265: MyApp.Router.dispatch/2
        (my_app) web/router.ex:1: MyApp.Router.do_call/2
        (my_app) lib/my_app/endpoint.ex:1: MyApp.Endpoint.phoenix_pipeline/1
        (my_app) lib/plug/debugger.ex:90: MyApp.Endpoint."call (overridable 3)"/2
        (my_app) lib/phoenix/endpoint/render_errors.ex:34: MyApp.Endpoint.call/2
        (plug) lib/plug/adapters/cowboy/handler.ex:15: Plug.Adapters.Cowboy.Handler.upgrade/4
        (cowboy) src/cowboy_protocol.erl:442: :cowboy_protocol.execute/4