Heey Sunkara,
In the stacktrace that you posted i see this line
The error is caused by not having read access on the UserRoles Entity in the System module. If you configure in the security settings to have read or read/write settings to it you should not get the error anymore.
Hope this helps.
Kind regards,
Edo
I had the same error as well!
Click on Security > User roles > Administration > User Management (all users must be selected) > OK and try to create new users in your application.
Hope this helps!
The User-fields are blanked out. As what are you logged in and are you using the default account pages?
If you have changed anything, let us know. Also, your mendix console should tell you the error (if using studio pro). If you have that, also share it.
This does look like a security issue though, access rules most likely for the role you are logged in as. 
 
hello
com.mendix.webui.WebUIException: Exception while retrieving data for 'Administration.Account_New.referenceSetSelector2' on document 'Administration.Account_New'
    at com.mendix.webui.actions.client.RetrieveAction.$anonfun$apply$3(RetrieveAction.scala:94)
Caused by: com.mendix.core.CoreRuntimeException: com.mendix.systemwideinterfaces.MendixRuntimeException: com.mendix.core.CoreRuntimeException: Exception occurred in action '{}', all database changes executed by this action were rolled back
    at com.mendix.basis.actionmanagement.ActionManager.executeSync(ActionManager.scala:108)
Caused by: com.mendix.systemwideinterfaces.MendixRuntimeException: com.mendix.core.CoreRuntimeException: Exception occurred in action '{}', all database changes executed by this action were rolled back
    at com.mendix.util.classloading.Runner$.withContextClassLoader(Runner.scala:23)
Caused by: com.mendix.core.CoreRuntimeException: Exception occurred in action '{}', all database changes executed by this action were rolled back
    at com.mendix.basis.actionmanagement.CoreActionHandlerImpl.processErrorState(CoreActionHandlerImpl.scala:153)
Caused by: com.mendix.basis.objectmanagement.member.MemberAccessDeniedException: Read access denied for member 'System.UserRoles' of object 'Administration.Account'
    at com.mendix.basis.objectmanagement.MendixObjectMemberImpl.checkReadAccess(MendixObjectMemberImpl.java:161)
    at com.mendix.basis.objectmanagement.MendixObjectMemberImpl.getValue(MendixObjectMemberImpl.java:208)
    at com.mendix.basis.objectmanagement.member.MendixObjectReferenceSetImpl.getValue(MendixObjectReferenceSetImpl.scala:54)
    at com.mendix.basis.objectmanagement.member.MendixObjectReferenceSetImpl.getValue(MendixObjectReferenceSetImpl.scala:21)
    at com.mendix.basis.objectmanagement.MendixObjectImpl.getValue(MendixObjectImpl.java:272)
    at com.mendix.implicits.package$MendixObjectOps$.get$extension(package.scala:24)
    at com.mendix.basis.action.user.RetrieveByPathAction.retrieveFromSameSide(RetrieveByPathAction.scala:26)
    at com.mendix.basis.action.user.RetrieveByPathAction.retrieveFromSameSide(RetrieveByPathAction.scala:12)
    at com.mendix.basis.action.user.RetrieveByPathBase.executeAction(RetrieveByPathBase.scala:71)
    at com.mendix.systemwideinterfaces.core.UserAction.execute(UserAction.java:58)
    at com.mendix.basis.actionmanagement.CoreActionHandlerImpl.doCall(CoreActionHandlerImpl.scala:71)
    at com.mendix.basis.actionmanagement.CoreActionHandlerImpl.call(CoreActionHandlerImpl.scala:48)
    at com.mendix.core.actionmanagement.internal.InternalCoreAction.call(InternalCoreAction.java:56)
    at com.mendix.basis.actionmanagement.ActionManager.$anonfun$executeSync$2(ActionManager.scala:104)
    at com.mendix.util.classloading.Runner$.withContextClassLoader(Runner.scala:20)
    at com.mendix.basis.actionmanagement.ActionManager.executeSync(ActionManager.scala:103)
    at com.mendix.basis.component.ExecutionCore.doExecuteSync(ExecutionCore.scala:148)
    at com.mendix.basis.component.ExecutionCore.doExecuteSync$(ExecutionCore.scala:147)
    at com.mendix.basis.component.InternalCore.doExecuteSync(InternalCore.scala:24)
    at com.mendix.basis.component.DataXPathCore.retrieveByPath(DataXPathCore.scala:50)
    at com.mendix.basis.component.DataXPathCore.retrieveByPath$(DataXPathCore.scala:42)
    at com.mendix.basis.component.InternalCore.retrieveByPath(InternalCore.scala:24)
    at com.mendix.webui.RetrieveUtils.$anonfun$retrieveByEntityPath$2(RetrieveUtils.scala:92)
    at scala.collection.immutable.List.flatMap(List.scala:293)
    at com.mendix.webui.RetrieveUtils.$anonfun$retrieveByEntityPath$1(RetrieveUtils.scala:92)
    at scala.collection.IterableOnceOps.foldLeft(IterableOnce.scala:675)
    at scala.collection.IterableOnceOps.foldLeft$(IterableOnce.scala:669)
    at scala.collection.AbstractIterator.foldLeft(Iterator.scala:1300)
    at com.mendix.webui.RetrieveUtils.retrieveByEntityPath(RetrieveUtils.scala:90)
    at com.mendix.webui.actions.client.RetrieveAction.$anonfun$retrieveAllByPath$1(RetrieveAction.scala:129)
    at scala.Option.map(Option.scala:242)
    at com.mendix.webui.actions.client.RetrieveAction.retrieveAllByPath(RetrieveAction.scala:129)
    at com.mendix.webui.actions.client.RetrieveAction.$anonfun$apply$3(RetrieveAction.scala:63)
    at scala.util.Either.map(Either.scala:382)
    at com.mendix.webui.actions.client.RetrieveAction.apply(RetrieveAction.scala:43)
    at com.mendix.webui.actions.client.RetrieveAction.apply(RetrieveAction.scala:28)
    at com.mendix.webui.actions.client.RegularClientAction$Helpers$.$anonfun$liftEither$1(RegularClientAction.scala:30)
    at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.$anonfun$apply$4(RegularClientAction.scala:56)
    at com.mendix.webui.requesthandling.helpers.StateHandling.withState(StateHandling.scala:45)
    at com.mendix.webui.requesthandling.helpers.StateHandling.withState$(StateHandling.scala:42)
    at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.withState(RegularClientAction.scala:46)
    at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.apply(RegularClientAction.scala:54)
    at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.apply(RegularClientAction.scala:46)
    at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$3(RegularClientAction.scala:120)
    at scala.util.Try$.apply(Try.scala:210)
    at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$2(RegularClientAction.scala:120)
    at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$2$adapted(RegularClientAction.scala:118)
    at com.mendix.webui.requesthandling.helpers.ContextHandling.$anonfun$inContext$7(ContextHandling.scala:58)
    at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
    at com.mendix.basis.actionmanagement.ActionMonitoring$.$anonfun$monitor$1(ActionMonitoring.scala:49)
    at com.mendix.util.classloading.Runner$.withContextClassLoader(Runner.scala:20)
    at com.mendix.basis.actionmanagement.ActionMonitoring$.monitor(ActionMonitoring.scala:49)
    at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext(ContextHandling.scala:58)
    at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext$(ContextHandling.scala:32)
    at com.mendix.webui.actions.client.RegularClientAction.inContext(RegularClientAction.scala:94)
    at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext(ContextHandling.scala:29)
    at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext$(ContextHandling.scala:21)
    at com.mendix.webui.actions.client.RegularClientAction.inContext(RegularClientAction.scala:94)
    at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$1(RegularClientAction.scala:118)
    at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
    at com.mendix.webui.requesthandling.helpers.ProfileHandling.profileRequest(ProfileHandling.scala:14)
    at com.mendix.webui.requesthandling.helpers.ProfileHandling.profileRequest$(ProfileHandling.scala:10)
    at com.mendix.webui.actions.client.RegularClientAction.profileRequest(RegularClientAction.scala:94)
    at com.mendix.webui.actions.client.RegularClientAction.execute(RegularClientAction.scala:115)
    at com.mendix.webui.requesthandling.ClientRequestHandler.handleAction(ClientRequestHandler.scala:106)
    at com.mendix.webui.requesthandling.ClientRequestHandler.processRequest(ClientRequestHandler.scala:79)
    at com.mendix.externalinterface.connector.RequestHandler.doProcessRequest(RequestHandler.java:37)
    at com.mendix.external.connector.MxRuntimeConnector.$anonfun$processRequest$1(MxRuntimeConnector.scala:54)
    at com.mendix.external.connector.MxRuntimeConnector.$anonfun$processRequest$1$adapted(MxRuntimeConnector.scala:54)
    at com.mendix.util.classloading.Runner$.withContextClassLoader(Runner.scala:20)
    at com.mendix.external.connector.MxRuntimeConnector.processRequest(MxRuntimeConnector.scala:54)
    at com.mendix.basis.impl.MxRuntimeImpl.processRequest(MxRuntimeImpl.scala:221)
    at com.mendix.m2ee.appcontainer.server.handler.RuntimeServlet.service(RuntimeServlet.scala:40)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:750)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:764)
    at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1665)
    at org.eclipse.jetty.websocket.servlet.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:170)
    at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
    at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1635)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:527)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:221)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1571)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:221)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1383)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:176)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:484)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1544)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:174)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1305)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:129)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
    at org.eclipse.jetty.server.Server.handle(Server.java:563)
    at org.eclipse.jetty.server.HttpChannel.lambda$handle$0(HttpChannel.java:505)
    at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:762)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:497)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:282)
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:314)
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:100)
    at org.eclipse.jetty.io.SelectableChannelEndPoint$1.run(SelectableChannelEndPoint.java:53)
    at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.runTask(AdaptiveExecutionStrategy.java:421)
    at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.consumeTask(AdaptiveExecutionStrategy.java:390)
    at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.tryProduce(AdaptiveExecutionStrategy.java:277)
    at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.lambda$new$0(AdaptiveExecutionStrategy.java:139)
    at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:411)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:933)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1077)
    at java.base/java.lang.Thread.run(Thread.java:829)