NPE in Xfire authenticating using spring-crowd connector

Crowd is throwing the following stacktrace when I attempt to authenticate with our crowd server. I can see activity on the crowd server itself, so the error message is misleading: it does find, and posts to, the service. Line 31 of the XFile class listed contains nothing that could NPE...is that exception coming from the server?

org.springframework.security.AuthenticationServiceException: Could not invoke service.. Nested exception is org.codehaus.xfire.fault.XFireFault: java.lang.NullPointerException; nested exception is org.codehaus.xfire.XFireRuntimeException: Could not invoke service.. Nested exception is org.codehaus.xfire.fault.XFireFault: java.lang.NullPointerException

at com.atlassian.crowd.integration.springsecurity.CrowdAuthenticationProvider.translateException(CrowdAuthenticationProvider.java:289)

at com.atlassian.crowd.integration.springsecurity.CrowdAuthenticationProvider.authenticateUsernamePassword(CrowdAuthenticationProvider.java:152)

at com.atlassian.crowd.integration.springsecurity.CrowdAuthenticationProvider.authenticate(CrowdAuthenticationProvider.java:90)

at org.springframework.security.providers.ProviderManager.doAuthentication(ProviderManager.java:188)

at org.springframework.security.AbstractAuthenticationManager.authenticate(AbstractAuthenticationManager.java:46)

at $AuthenticationManager_12edf2b5dab.authenticate($AuthenticationManager_12edf2b5dab.java)

at org.springframework.security.ui.webapp.AuthenticationProcessingFilter.attemptAuthentication(AuthenticationProcessingFilter.java:82)

at org.springframework.security.ui.AbstractProcessingFilter.doFilterHttp(AbstractProcessingFilter.java:258)

at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)

at nu.localhost.tapestry5.springsecurity.services.internal.HttpServletRequestFilterWrapper.service(HttpServletRequestFilterWrapper.java:52)

at $HttpServletRequestFilter_12edf2b5dc8.service($HttpServletRequestFilter_12edf2b5dc8.java)

at $HttpServletRequestHandler_12edf2b5dd2.service($HttpServletRequestHandler_12edf2b5dd2.java)

at nu.localhost.tapestry5.springsecurity.services.internal.HttpServletRequestFilterWrapper$1.doFilter(HttpServletRequestFilterWrapper.java:56)

at org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:235)

at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)

at nu.localhost.tapestry5.springsecurity.services.internal.HttpServletRequestFilterWrapper.service(HttpServletRequestFilterWrapper.java:52)

at $HttpServletRequestFilter_12edf2b5dc7.service($HttpServletRequestFilter_12edf2b5dc7.java)

at $HttpServletRequestHandler_12edf2b5dd2.service($HttpServletRequestHandler_12edf2b5dd2.java)

at org.apache.tapestry5.services.TapestryModule$2.service(TapestryModule.java:729)

at $HttpServletRequestHandler_12edf2b5dd2.service($HttpServletRequestHandler_12edf2b5dd2.java)

at $HttpServletRequestHandler_12edf2b5dc6.service($HttpServletRequestHandler_12edf2b5dc6.java)

at org.apache.tapestry5.TapestryFilter.doFilter(TapestryFilter.java:127)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:244)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:589)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:541)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:383)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:288)

at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)

at java.lang.Thread.run(Thread.java:680)

Caused by: org.codehaus.xfire.XFireRuntimeException: Could not invoke service.. Nested exception is org.codehaus.xfire.fault.XFireFault: java.lang.NullPointerException

at org.codehaus.xfire.client.XFireProxy.handleRequest(XFireProxy.java:92)

at org.codehaus.xfire.client.XFireProxy.invoke(XFireProxy.java:57)

at $Proxy95.findGroupMemberships(Unknown Source)

at com.atlassian.crowd.service.soap.client.SecurityServerClientImpl.findGroupMemberships(SecurityServerClientImpl.java:1393)

at com.atlassian.crowd.service.cache.CachingGroupMembershipManager$Server.getMemberships(CachingGroupMembershipManager.java:320)

at com.atlassian.crowd.service.cache.CachingGroupMembershipManager.getMemberships(CachingGroupMembershipManager.java:115)

at com.atlassian.crowd.integration.springsecurity.user.CrowdUserDetailsServiceImpl.getAuthorities(CrowdUserDetailsServiceImpl.java:123)

at com.atlassian.crowd.integration.springsecurity.user.CrowdUserDetailsServiceImpl.loadUserByUsername(CrowdUserDetailsServiceImpl.java:42)

at com.atlassian.crowd.integration.springsecurity.RemoteCrowdAuthenticationProvider.loadUserByUsername(RemoteCrowdAuthenticationProvider.java:52)

at com.atlassian.crowd.integration.springsecurity.CrowdAuthenticationProvider.authenticateUsernamePassword(CrowdAuthenticationProvider.java:146)

... 37 more

Caused by: org.codehaus.xfire.fault.XFireFault: java.lang.NullPointerException

at org.codehaus.xfire.fault.Soap11FaultSerializer.readMessage(Soap11FaultSerializer.java:31)

at org.codehaus.xfire.fault.SoapFaultSerializer.readMessage(SoapFaultSerializer.java:28)

at org.codehaus.xfire.soap.handler.ReadHeadersHandler.checkForFault(ReadHeadersHandler.java:111)

at org.codehaus.xfire.soap.handler.ReadHeadersHandler.invoke(ReadHeadersHandler.java:67)

at org.codehaus.xfire.handler.HandlerPipeline.invoke(HandlerPipeline.java:131)

at org.codehaus.xfire.client.Client.onReceive(Client.java:406)

at org.codehaus.xfire.transport.http.HttpChannel.sendViaClient(HttpChannel.java:139)

at org.codehaus.xfire.transport.http.HttpChannel.send(HttpChannel.java:48)

at org.codehaus.xfire.handler.OutMessageSender.invoke(OutMessageSender.java:26)

at org.codehaus.xfire.handler.HandlerPipeline.invoke(HandlerPipeline.java:131)

at org.codehaus.xfire.client.Invocation.invoke(Invocation.java:79)

at org.codehaus.xfire.client.Invocation.invoke(Invocation.java:114)

at org.codehaus.xfire.client.Client.invoke(Client.java:336)

at org.codehaus.xfire.client.XFireProxy.handleRequest(XFireProxy.java:77)

... 46 more