Confluence Pages don't render, cannot create/edit content

Question

We are upgrading from Confluence 3.2 to Confluence 3.5 to Confluence 4.3. This instance has a number of plugins, some of which are no longer supported (this may or may not relate to the issues we are seeing). Any time we create a new page or edit an existing one Confluence throws an error when the page is saved. We also see this error in other places in Confluence.

Cause

javax.servlet.ServletException: Servlet execution threw an exception

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:313)

caused by: java.lang.NoClassDefFoundError: org/apache/xerces/dom/DocumentFragmentImpl

at org.apache.xerces.dom.CoreDocumentImpl.createDocumentFragment(Unknown Source)

Pepe · Accepted Answer

Tried and true - restarted confluence (not sure why I didn't think of that sooner). I'm not sure what happened but in all the poking around we must have jarred some plugin into behaving badly.