I am in change of upgrading an older Apache Tomcat installation from 7.0.50 to 7.0.109. My issues started with any version greater than 7.0.50 it would cause JSTL to stop working.
My solution was to upgrade from jstl.jar and standard.jar to jstl-1.2.jar then add this line of code to the top of each jsp page.
<%@page isELIgnored="false" %>
I finally have a solution but I don't understand why the above line was needed.
What I tried
I tried multiple installs of Tomcat versions 7.0.55 through 7.0.109 all had the same JSTL error.
I tried Javax JSTL, I tried Jakarta JSTL, still had the JSTL error. Both worked after adding the isELIgnored="false".