500 Internal Server Error

oracle.portal.provider.v2.ProviderException: Caught SchemaException
at oracle.portal.utils.v2.ContainerException.fillInStackTrace(Unknown Source)
at java.lang.Throwable.<init>(Throwable.java:195)
at java.lang.Exception.<init>(Exception.java:41)
at oracle.portal.utils.v2.ContainerException.<init>(Unknown Source)
at oracle.portal.provider.v2.ProviderException.<init>(Unknown Source)
at oracle.discoverer.applications.portletprovider.framework.DiscovererProviderLoader.initializePortletProvider(DiscovererProviderLoader.java:380)
at oracle.discoverer.applications.portletprovider.framework.DiscovererProviderLoader.init(DiscovererProviderLoader.java:163)
at oracle.webdb.provider.v2.adapter.soapV1.ProviderAdapter.init(Unknown Source)
at oracle.webdb.provider.v2.adapter.SOAPServlet.locateService(Unknown Source)
at oracle.webdb.provider.v2.adapter.SOAPServlet.doHTTPCall(Unknown Source)
at oracle.webdb.provider.v2.adapter.SOAPServlet.service(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:824)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:330)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:830)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.AJPRequestHandler.run(AJPRequestHandler.java:224)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.AJPRequestHandler.run(AJPRequestHandler.java:133)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:192)
at java.lang.Thread.run(Thread.java:534)