diff --git a/AssemblyVersion.cs b/AssemblyVersion.cs
index 8e9195d..9431da0 100644
--- a/AssemblyVersion.cs
+++ b/AssemblyVersion.cs
@@ -16,5 +16,5 @@ using System.Reflection;
 //
 // You can specify all the values or you can default the Revision and Build Numbers 
 // by using the '*' as shown below:
-[assembly: AssemblyVersion("3.0.1.455")]
-[assembly: AssemblyFileVersion("3.0.1.455")]
+[assembly: AssemblyVersion("3.0.1.456")]
+[assembly: AssemblyFileVersion("3.0.1.456")]
diff --git a/Core/SessionFacade.cs b/Core/SessionFacade.cs
index a5a86e6..0a3e94e 100644
--- a/Core/SessionFacade.cs
+++ b/Core/SessionFacade.cs
@@ -94,10 +94,13 @@ namespace ScrewTurn.Wiki {
 				if(groups == null || groups.Length == 0) {
 					UserInfo current = GetCurrentUser();
 					if(current != null) {
-						groups = new UserGroup[current.Groups.Length];
-						for(int i = 0; i < groups.Length; i++) {
-							groups[i] = Users.FindUserGroup(current.Groups[i]);
+						// This check is necessary because after group deletion the session might contain outdated data
+						List<UserGroup> temp = new List<UserGroup>(current.Groups.Length);
+						for(int i = 0; i < current.Groups.Length; i++) {
+							UserGroup tempGroup = Users.FindUserGroup(current.Groups[i]);
+							if(tempGroup != null) temp.Add(tempGroup);
 						}
+						groups = temp.ToArray();
 					}
 					else {
 						groups = new UserGroup[] { Users.FindUserGroup(Settings.AnonymousGroup) };
diff --git a/Core/UsersStorageProvider.cs b/Core/UsersStorageProvider.cs
index 0521411..3dac62b 100644
--- a/Core/UsersStorageProvider.cs
+++ b/Core/UsersStorageProvider.cs
@@ -643,6 +643,7 @@ namespace ScrewTurn.Wiki {
 				DumpUserGroups(result.ToArray());
 
 				groupsCache = null;
+				usersCache = null;
 
 				return result.Count == allGroups.Length - 1;
 			}