{error,{bad_return,{{xxapp,start,[normal,[]]},ok}}}

通过appllcation启动，报以下错误；

1> application:start(server).

{error,{bad_return,{ {server_app,start,[normal,[]]},ok}}}


=INFO REPORT==== 17-Mar-2016::19:49:20 ===
    application: server
    exited: {bad_return,{ {server_app,start,[normal,[]]},ok}}

    type: temporary

xx_app:start/2 只能返回  {ok,Pid} ,一般是supervisor:start_link 启动的 根监督树的结果;否则application：start（app）方式会启动失败，报以上错误.