JIRA support request page broken

Going to http://<host>/secure/admin/jira/JiraSupportRequest!default.jspa now results in:

HTTP Status 404 - Could not execute action [JiraSupportRequest!default]:Action 'admin.JiraStudioSupportRequest' not found or could not be initialized: Class not found<p><small><small><pre>java.lang.IllegalArgumentException: Action 'admin.JiraStudioSupportRequest' not found or could not be initialized: Class not found at com.atlassian.jira.config.webwork.JiraActionFactory$JiraPluginActionFactory.getActionImpl(JiraActionFactory.java:60) at webwork.action.factory.ScriptActionFactoryProxy.getActionImpl(ScriptActionFactoryProxy.java:54) at webwork.action.factory.XMLActionFactoryProxy.getActionImpl(XMLActionFactoryProxy.java:54) at
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