Error in edit mode, could be related to EPi Mail

November Happy Hour will be moved to Thursday December 5th.

Value cannot be null.
Parameter name: group

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.ArgumentNullException: Value cannot be null.
Parameter name: group

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:

[ArgumentNullException: Value cannot be null.
Parameter name: group]
   EPiServer.Common.Security.Internal.SecurityHandler.GetGroupUsers(IGroup group) +478
   ThinkBig.Web.UI.EPiServerMail.ProjectMembersSource.ConstructRecipientContainer(Club club) +808
   ThinkBig.Web.UI.EPiServerMail.ProjectMembersSource.GetRecipientContainers(ISite site, Int32 page, Int32 pageSize, Int32& totalItems, RecipientContainerSortOrder[] order) +792
   EPiServer.Mail.Core.EP.Web.ComposeNewMailControl.BindRecipientContainers() +416
   EPiServer.Mail.Core.EP.Web.ComposeNewMailControl.InitializeRecipientsSection() +675
   EPiServer.Mail.Core.EP.Web.ComposeNewMailControl.Page_Init(Object sender, EventArgs e) +55
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +42
   System.Web.UI.Control.OnInit(EventArgs e) +132
   System.Web.UI.Control.InitRecursive(Control namingContainer) +143
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1477

Error in edit mode, could be related to EPi Mail

Server Error in '/' Application.

Value cannot be null.Parameter name: group

Value cannot be null.
Parameter name: group