1. If this is your first time running Bitbucket Server or you have recently added applications or made changes to the system, investigate what's running on port 7990 (Default port for Bitbucket Server) .
2. If Bitbucket Server was not shut down properly, you can restart the machine or kill the process:

1. Hit Ctrl-alt-delete and look at open programs. Look for {{java.exe}}.
2. From a command window, run {{netstat -an}}. Check which ports are in use. You can identify which application is running this way, then close it from the Task Manager.

Run {{ps -aux \| grep java}}. This will show the java processes running and their process ids. You can kill a process with the command {{kill -9 <pid>}}.

3. If there is another application running on that port and you wish to continue running it on port 7990, you will need to change the default listening port for Bitbucket Server. Follow the steps on Change the port Bitbucket listens on to change the port for Bitbucket Server.