Root causes for HTTP 404 errors:

Based on symptoms that customers report, we can usually narrow the problem down to one of two types:
1) Page cannot be displayed or JSP/JSF error
2) WebGroup/virtual host not defined
STEP 1. Page cannot be displayed or JSP/JSF error
When we have a “Page cannot be displayed” error and the resource is a JSP page, JSF page, or servlet, or the browser is displaying a JSP error, initiate the following actions:
a. Verify that the Web server plug-in is working correctly
b. Verify that the URL that is causing the error is specified correctly
c. Verify that the Web server is responding
d. Verify that the application is running