This happens if

• you have JCR authentication module set to optional
• user does not exist in magnolia.
  We are building external login modules to authenticate/authorise to custom data sources.

Exception on login,

16:25:51,990 ERROR [[default]] Servlet.service() for servlet default threw exception
java.util.NoSuchElementException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:790)
at java.util.HashMap$KeyIterator.next(HashMap.java:823)
at info.magnolia.cms.security.MgnlUserManager.getUser(MgnlUserManager.java:114)
at info.magnolia.cms.security.DelegatingUserManager$5.delegate(DelegatingUserManager.java:96)
at info.magnolia.cms.security.DelegatingUserManager.delegateUntilNotNull(DelegatingUserManager.java:130)
at info.magnolia.cms.security.DelegatingUserManager.getUser(DelegatingUserManager.java:94)
at info.magnolia.cms.security.SecuritySupportBase.authenticate(SecuritySupportBase.java:66)
at info.magnolia.cms.security.auth.login.LoginHandlerBase.authenticate(LoginHandlerBase.java:47)
at info.magnolia.cms.security.auth.login.FormLogin.handle(FormLogin.java:74)
at info.magnolia.cms.security.auth.login.LoginFilter.doFilter(LoginFilter.java:65)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:70)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:71)
at info.magnolia.enterprise.registration.RegistrationFilter.doFilter(RegistrationFilter.java:55)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:70)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:71)
at info.magnolia.cms.filters.ContentTypeFilter.doFilter(ContentTypeFilter.java:73)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:70)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:71)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:65)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:73)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:73)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:73)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:73)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:73)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:73)
at info.magnolia.cms.filters.CompositeFilter.doFilter(CompositeFilter.java:64)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:70)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:71)
at info.magnolia.cms.filters.ContextFilter.doFilter(ContextFilter.java:72)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:70)
at info.magnolia.cms.filters.MgnlFilterChain.doFilter(MgnlFilterChain.java:71)
at info.magnolia.cms.filters.CompositeFilter.doFilter(CompositeFilter.java:64)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:70)
at info.magnolia.cms.filters.MgnlMainFilter.doFilter(MgnlMainFilter.java:98)
at info.magnolia.cms.filters.MgnlMainFilter.doFilter(MgnlMainFilter.java:195)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
at java.lang.Thread.run(Thread.java:613)