Recently I experience this issue, even after a fresh tomcat and eclipse installation, I add the server on eclipse and when I run it, it does show 404 page but when I manually run it it works smoothly, so the solution is very simple.
- Stop your server and right click on the server and choose Add and remove and remove all the projects on tomcat
- Right click on the server again and click on clean, this will clean up
- Right click on the tomcat again click on properties and choose switch location, this will navigate to the right path
- And last of all double click on tomcat and on the menu you will see “server locations” here choose the “use tomcat installation(takes control of Tomcat installation)” option save it and start tomcat and see the outcome