How to Fix Tomcat 404 Error

1. Tomcat 404 Error in Java
2. Tomcat 404 Error in Eclipse

This tutorial demonstrates how to troubleshoot the Tomcat 404 error in Java.

Tomcat 404 Error in Java

While using the apache Tomcat server for web development in Java, the most common error is the HTTP Status 404. This error means the server cannot find the required resource.

The required file can be anything like HTML, Image Resource or JSP.

Most of the time, the error occurs when the required reference is not present or is referenced incorrectly. The error looks like this:

There are three main reasons for this error in Apache Tomcat.

1. The URL is Case Sensitive

   The Tomcat URLs are case sensitive, so whenever you are trying to write the URL by yourself, make sure that it is also correct in its case. Otherwise, it will throw the 404 status error.

2. The Servlets Do Not Handle the URL

   The @Webservlet() is also used to handle the URL/demo, but when requesting the URL, it can be URL/this_demo, which is a different reference. This can be fixed by using the URL mapping and referencing the URL correctly.

   See example:

   @WebServlet("/demo")
   public class Demo extends HttpServlet {
     // Your code here.
   }
   

   Now, if the website requests the URL this_demo, we can solve it by changing the demo to this_demo in the URL mapping.

3. Resource Forward by Servlets Does Not Exist

   When the resource forwarded by servlets does not exist, the Tomcat will throw a 404 error. Make sure the resource forwarded exists and the name of that resource is correct.

   For example, if we are referencing the DemoForm.jsp but the real name of that resource is Demo_Form.jsp, it will throw the 404 status error. We can change the DemoForm.jsp to Demo_Form.jsp to solve this error.

   See example:

   String Demo_Form = "frontend/Demo_Form.jsp";
   RequestDispatcher Request_Dispatcher = request.getRequestDispatcher(Demo_Form);
   Request_Dispatcher.forward(request, response);
   

Tomcat 404 Error in Eclipse

While working with Tomcat in Eclipse IDE, the same 404 error can occur even if we have managed all the solutions above. Sometimes, even if the Tomcat starts, the browser will throw the 404 error while working with Eclipse IDE.

This error is because Tomcat is not configured correctly in the Eclipse IDE. To solve this issue in Eclipse, follow the steps below.