What is the default Jenkins password?

Here is how you can fix it:

• Stop Jenkins
• Go go edit /var/lib/jenkins/config.xml
• Change <useSecurity>true</useSecurity> to false
• Restart Jenkins: sudo service jenkins restart
• Navigate to the Jenkins dashboard to the "Configure Security" option you likely used before. This time, setup security the same as before, BUT set it to allow anyone to do anything, and allow user signup.
• Go to www.yoursite.com/securityRealm/addUser and create a user
• Then go change allow anyone to do anything to whatever you actually want users to be able to do. In my case, it is allow logged in users to do anything.

If you installed using apt-get in ubuntu 14.04, you will found the default password in /var/lib/jenkins/secrets/initialAdminPassword location.

Before installing jenkins, create a user named jenkins and set password there. Then after installing jenkins you can use the password you created.