OpenTripPlanner Server won't start

I was following this tutorial to learn how to setup and run OpenTripPlanner : https://github.com/marcusyoung/otp-tutorial/blob/master/intro-otp.pdf

Everything goes well, until I want to start the server with this command :
java -Xmx2G -jar otp.jar --router current --graphs graphs --server

I get this on loop :

http://localhost:8080 shows nothing, tried the next command that selects different ports but the same thing happens.

Any idea how to resolve this problem?