Selenium: Invalid “already running” error when starting server

Question

I am trying to get the Selenium server up and running. However, when I type:

 java -jar selenium-server-standalone-2.0b3.jar

I get an Exception: 

Selenium is already running on port 4444. Or some other service is.

I have tried to stop it, just in case it really is running:

http://localhost:4444/selenium-server/driver/?cmd=shutDown

That gets me the message:

ERROR Server Exception: sessionId should not be null; has this session been started yet?

If I just write:

http://localhost:4444/

I get:

HTTP ERROR: 403

Forbidden for Proxy

Ideas?

Answer 1

This worked for me:

http://localhost:4444/selenium-server/driver/?cmd=shutDownSeleniumServer

If selenium server is already running on port 4444 then it will shut down the server and says OKOK if selenium is not running on this port 4444 then by hitting above URL will give you "Unable to connect"