I have a similar problem to the one here DispatcherServlet cannot be cast to Servlet which is when running a new Spring MVC project using Eclipse. However, all the answers suggest a solution using Maven and I'm not using Maven.
I searched for a day for this problem but no solution.
INFO: Starting Servlet engine: [Apache Tomcat/10.0.4]
Mar 22, 2021 9:59:10 AM org.apache.catalina.util.SessionIdGeneratorBase createSecureRandom
WARNING: Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took
[447] milliseconds.
Mar 22, 2021 9:59:10 AM org.apache.jasper.servlet.TldScanner scanJars
INFO: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for
this logger for a complete list of JARs that were scanned but no TLDs were found in them.
Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
Mar 22, 2021 9:59:11 AM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet [dispatcher] as unavailable
Mar 22, 2021 9:59:11 AM org.apache.catalina.core.StandardContext loadOnStartup
SEVERE: Servlet [dispatcher] in web application [/spring-mvc-demo] threw load() exception
java.lang.ClassCastException: class org.springframework.web.servlet.DispatcherServlet cannot
be cast to class jakarta.servlet.Servlet (org.springframework.web.servlet.DispatcherServlet
is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader
@62e70ea3; jakarta.servlet.Servlet is in unnamed module of loader java.net.URLClassLoader
@8bd1b6a)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1043)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:984)