Greetings, I just took the plunge and upgraded a site from 5.6.3 to 6.2 - It took some time, but using the suggested upgrade path everything snapped into place without any error.  Site is operational in general, but messaging and the social modules are not working.

In particular:

a) Send To Box in compose message is always empty and no user evers appear when it tries to search

b)Member Directory Module is unresponsive and always stuck on the "loading" graphic

c)When trying to access another user's profile I always get redirected to my own - but I suppose that's due to the issue in messaging itself.

The only error that appears in the event viewer is the following:

Message: System.Threading.ThreadAbortException: Thread was being aborted. at System.Threading.Thread.AbortInternal() at System.Threading.Thread.Abort(Object stateInfo) at System.Web.HttpResponse.End() at DotNetNuke.Modules.CoreMessaging.View.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.AddedControl(Control control, Int32 index) at DotNetNuke.UI.Modules.ModuleHost.CreateChildControls() at System.Web.UI.Control.EnsureChildControls() at DotNetNuke.UI.Containers.Container.get_ModuleControl() at DotNetNuke.UI.Containers.Container.ProcessModule() at DotNetNuke.UI.Skins.Pane.InjectModule(ModuleInfo module)

which leads me to believe that the problem lies somehow with CoreMessaging

I get the same thing... the whole social thing doesn't seem to work at all in my PowerDNN hosted solution. I can't post anything to a group and the message center and member directory modules just return those same errors you posted. Looking at the response that fails in Chrome shows a 500 error with the following ASP.NET response. At this point, I'm giving up on trying to use these overhyped features - I'll just code a facebook/twitter feed into my site and be done with it. It's not like you ever get any help on these forums for bugs anyway.

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.Mvc.<>c__DisplayClass6.b__1(ValueProviderFactory factory) +27
System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +151
System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +177
System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +406
System.Linq.Enumerable.ToList(IEnumerable`1 source) +58
System.Web.Mvc.ValueProviderFactoryCollection.GetValueProvider(ControllerContext controllerContext) +251
System.Web.Mvc.ControllerBase.get_ValueProvider() +25
System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +62
System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +105
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +329
System.Web.Mvc.Controller.ExecuteCore() +115
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +42
System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
System.Web.Mvc.<>c__DisplayClass8.b__4() +34
System.Web.Mvc.Async.<>c__DisplayClass1.b__0() +21
System.Web.Mvc.Async.<>c__DisplayClass8`1.b__7(IAsyncResult _) +12
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +55
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +30
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8970061
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184