org.apache.jasper.JasperException: java.lang.ClassNotFoundException: org.apache.jsp.register_jsp

This error message indicates that the web application is unable to find the compiled JSP file for the "register.jsp" page. This could be caused by a few different issues:

1. The JSP file may not have been compiled yet. Make sure that the JSP file has been compiled by the server before accessing it.

2. The compiled JSP file may have been deleted or moved. Check to make sure that the compiled JSP file exists in the expected location.

3. The classpath may not be set up correctly. Check that the classpath includes the directory where the compiled JSP files are stored.

4. There may be a typo or error in the JSP file itself that is preventing it from being compiled correctly. Check the JSP file for any syntax errors or other issues.

To resolve this issue, try recompiling the JSP file and making sure that the compiled file is in the correct location. Check the classpath to make sure that it includes the directory where the compiled JSP files are stored. If you are still having issues, check the JSP file for any syntax errors or other issues that may be preventing it from being compiled correctly.