Signal Server is stopping after showing message null

[kkscwcd]

Hi,
I builded the latest signal server code and configured the yml configuration file, Database migration is done perfectly but when i try to start the server, these messages are getting printed and it stop.

D:\Fl\Ahmed_SignalApp\SignalServerLatest>java -jar TextSecureServer-1.66.jar server sample.yml
INFO [2018-02-12 11:19:07,354] org.eclipse.jetty.util.log: Logging initialized @1518ms to org.eclipse.jetty.util.log.Slf4jLog
INFO [2018-02-12 11:19:07,528] io.dropwizard.server.DefaultServerFactory: Registering jersey handler with root path prefix: /
INFO [2018-02-12 11:19:07,529] io.dropwizard.server.DefaultServerFactory: Registering admin handler with root path prefix: /
null

I am attaching screenshot, any help will appreciated as i am not able to understand from which point this error is coming