Error when adding member to team

Using JIRA 6.4.7, trial version of Portfolio build: 1.12.0

When we attempt to add members to a team, we're getting "Key should not be null". Various users have attempted include Administrators. Any ideas what might be wrong?
Full error message:
com.atlassian.jira.util.dbc.Assertions$NullArgumentException :key should not be null!

at com.atlassian.jira.util.dbc.Assertions.notNull:29
at com.atlassian.jira.user.DelegatingApplicationUser.<init>:20
at com.atlassian.jira.user.util.DefaultUserManager.getAllApplicationUsers:105
at sun.reflect.GeneratedMethodAccessor7042.invoke:-1
at sun.reflect.DelegatingMethodAccessorImpl.invoke:-1
at java.lang.reflect.Method.invoke:-1
at com.atlassian.plugin.osgi.hostcomponents.impl.DefaultComponentRegistrar$ContextClassLoaderSettingInvocationHandler.invoke:134
at com.sun.proxy.$Proxy330.getAllApplicationUsers:-1
at sun.reflect.GeneratedMethodAccessor7042.invoke:-1
at sun.reflect.DelegatingMethodAccessorImpl.invoke:-1
at java.lang.reflect.Method.invoke:-1
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection:307
at org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.doInvoke:58
at org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.invoke:62
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed:171
at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed:131
at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke:119
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed:171
at org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invokeUnprivileged:56
at org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invoke:39
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed:171
at org.springframework.osgi.service.importer.support.LocalBundleContextAdvice.invoke:59
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed:171
at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed:131
at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke:119
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed:171
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke:204
at com.sun.proxy.$Proxy3269.getAllApplicationUsers:-1
at com.atlassian.jpo.jira.api.user.UserSearchServiceBridge63.findUsersByName:54
at com.radiantminds.roadmap.jira.common.components.extension.users.JiraUserExtension.listUsers:220
at com.radiantminds.roadmap.common.rest.services.persons.PlanUserServiceHandler$Impl.listAllUsersWithPost:94
at sun.reflect.GeneratedMethodAccessor7118.invoke:-1
at sun.reflect.DelegatingMethodAccessorImpl.invoke:-1
at java.lang.reflect.Method.invoke:-1
at com.radiantminds.roadmap.common.handlers.SecuredInvocationHandler.invoke:159
at com.sun.proxy.$Proxy4093.listAllUsersWithPost:-1
at com.radiantminds.roadmap.common.rest.services.persons.PlanUserService.listAllUsersWithPost:56
at sun.reflect.GeneratedMethodAccessor7117.invoke:-1
at sun.reflect.DelegatingMethodAccessorImpl.invoke:-1
at java.lang.reflect.Method.invoke:-1
at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper$ResponseOutInvoker$1.invoke:234
at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper$1.intercept:100
at com.atlassian.plugins.rest.common.interceptor.impl.DefaultMethodInvocation.invoke:61
at com.atlassian.plugins.rest.common.expand.interceptor.ExpandInterceptor.intercept:38
at com.atlassian.plugins.rest.common.interceptor.impl.DefaultMethodInvocation.invoke:61
at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper.invokeMethodWithInterceptors:132
at com.atlassian.plugins.rest.common.interceptor.impl.DispatchProviderHelper$ResponseOutInvoker._dispatch:230
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch:75
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept:288
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept:108
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept:147
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept:84
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest:1469
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest:1400
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest:1349
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest:1339
at com.sun.jersey.spi.container.servlet.WebComponent.service:416
at com.sun.jersey.spi.container.servlet.ServletContainer.service:537
at com.atlassian.plugins.rest.module.RestDelegatingServletFilter$JerseyOsgiServletContainer.doFilter:178
at com.sun.jersey.spi.container.servlet.ServletContainer.doFilter:795
at com.atlassian.plugins.rest.module.RestDelegatingServletFilter.doFilter:73
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:77
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:63
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.plugins.rest.module.servlet.RestServletUtilsUpdaterFilter.doFilterInternal:26
at com.atlassian.plugins.rest.module.servlet.RestServletUtilsUpdaterFilter.doFilter:40
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.applinks.core.rest.context.ContextFilter.doFilter:25
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.mywork.client.filter.ServingRequestsFilter.doFilter:37
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.plugins.cors.CorsFilter.doFilter:65
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsSiteMeshFixupFilter.doFilter:36
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsDispatcherFilter.doFilter:60
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsSiteMeshFilter.doFilter:92
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsMatcherFilter.doFilter:56
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.labs.botkiller.BotKillerFilter.doFilter:36
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:77
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:63
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.web.filters.accesslog.AccessLogFilter.executeRequest:107
at com.atlassian.jira.web.filters.accesslog.AccessLogFilter.doFilter:91
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.security.xsrf.XsrfTokenAdditionRequestFilter.doFilter:54
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.web.filters.pagebuilder.PageBuilderFilter.doFilter:90
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.web.filters.CommittedResponseHtmlErrorRecoveryFilter.doFilter:63
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:46
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsCombinedMatchDispatcherFilter.doFilter:61
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:77
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:63
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.seraph.filter.SecurityFilter.doFilter:239
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.security.auth.trustedapps.filter.TrustedApplicationsFilter.doFilter:100
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.seraph.filter.BaseLoginFilter.doFilter:172
at com.atlassian.jira.web.filters.JiraLoginFilter.doFilter:70
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:46
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.oauth.serviceprovider.internal.servlet.OAuthFilter.doFilter:79
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.plugins.rest.module.servlet.RestSeraphFilter.doFilter:40
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsCombinedMatchDispatcherFilter.doFilter:61
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:77
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:63
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.johnson.filters.AbstractJohnsonFilter.doFilter:71
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite:176
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules:145
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest:92
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter:394
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:46
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.analytics.client.filter.JiraAnalyticsFilter.doFilter:40
at com.atlassian.analytics.client.filter.AbstractHttpFilter.doFilter:32
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter:70
at com.atlassian.prettyurls.filter.PrettyUrlsCombinedMatchDispatcherFilter.doFilter:61
at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter.doFilter:78
at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter:42
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:77
at com.atlassian.plugin.servlet.filter.ServletFilterModuleContainerFilter.doFilter:63
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.web.filters.steps.ChainedFilterStepRunner.doFilter:87
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.core.filters.cache.AbstractCachingFilter.doFilter:33
at com.atlassian.core.filters.AbstractHttpFilter.doFilter:31
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.core.filters.encoding.AbstractEncodingFilter.doFilter:41
at com.atlassian.core.filters.AbstractHttpFilter.doFilter:31
at com.atlassian.jira.web.filters.PathMatchingEncodingFilter.doFilter:45
at com.atlassian.core.filters.AbstractHttpFilter.doFilter:31
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.startup.JiraStartupChecklistFilter.doFilter:79
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.web.filters.MultipartBoundaryCheckFilter.doFilter:41
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.jira.web.filters.steps.ChainedFilterStepRunner.doFilter:87
at com.atlassian.jira.web.filters.JiraFirstFilter.doFilter:61
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at com.atlassian.gzipfilter.GzipFilter.doFilterInternal:121
at com.atlassian.gzipfilter.GzipFilter.doFilter:92
at com.atlassian.jira.web.filters.gzip.JiraGzipFilter.doFilter:56
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter:241
at org.apache.catalina.core.ApplicationFilterChain.doFilter:208
at org.apache.catalina.core.StandardWrapperValve.invoke:220
at org.apache.catalina.core.StandardContextValve.invoke:122
at org.apache.catalina.authenticator.AuthenticatorBase.invoke:501
at org.apache.catalina.core.StandardHostValve.invoke:171
at org.apache.catalina.valves.ErrorReportValve.invoke:103
at org.apache.catalina.core.StandardEngineValve.invoke:116
at org.apache.catalina.valves.AccessLogValve.invoke:950
at org.apache.catalina.connector.CoyoteAdapter.service:408
at org.apache.coyote.ajp.AjpProcessor.process:190
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process:611
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run:314
at java.util.concurrent.ThreadPoolExecutor.runWorker:-1
at java.util.concurrent.ThreadPoolExecutor$Worker.run:-1
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run:61
at java.lang.Thread.run:-1