Cannot add new portlet to dashboard with older Tomcat versions

Adding a new portlet to the personal dashboard results in some lengthy exception stacktrace (I can provide the rest if needed, but I doubt it's helpful):

Could not execute action [saveportlet!default]:Action 'saveportlet' not found or could not be initialized: java.lang.ClassNotFoundException: saveportlet<p><small><small><pre>java.lang.IllegalArgumentException: Action 'saveportlet' not found or could not be initialized: java.lang.ClassNotFoundException: saveportlet at com.atlassian.jira.web.util.component.PicoJavaActionFactory.getActionImpl(PicoJavaActionFactory.java:64)