Server http:/localhost:8080 requires a user name and a password. The server says: XDB

This is http authentication. You can find username and password inside users.xml WEB-INF directory if any. otherwise you have to edit or remove security-constraint element from web.xml file

UPDATE Sorry, I haven't noticed XDB. check if Oracle and tomcat using same port. Update anyone of them

Some other application(like oracle) is using the same port number. So you should change the tomcat port number in apachetomcat/conf/server.xml

Privious--->

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

Updated ---->

<Connector port="8088" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

This is caused because there is a database running on your computer. In my case, it was an Oracle data base. By default, everytime you start your computer, the services of the database automatically starts.

Go to Start >> find Oracle or whatever data-base in the list of programms >> and manually stop the database. It appears that there is a conflict of port.