I ran into this problem debugging play framework version 2.x, turned out the server hadn't been started even though the play debug run command was issued. After a first request to the webserver which caused the play framework to really start the application at port 9000, I was able to connect properly to the debug port 9999 from eclipse.
[info] play - Application started (Dev)
The text above was shown in the console when the message above appeared, indicating why eclipse couldn't connect before first http request.
