Index: Core/Common/src/Core.Common.Base/Service/Activity.cs
===================================================================
diff -u -r67284323e2785c651633d9c52049ba12a9c70e6a -rd24dba0f0c60fe14353ac3c5622e12a9d5bd758d
--- Core/Common/src/Core.Common.Base/Service/Activity.cs	(.../Activity.cs)	(revision 67284323e2785c651633d9c52049ba12a9c70e6a)
+++ Core/Common/src/Core.Common.Base/Service/Activity.cs	(.../Activity.cs)	(revision d24dba0f0c60fe14353ac3c5622e12a9d5bd758d)
@@ -122,6 +122,11 @@
         /// </summary>
         public void Finish()
         {
+            if (State == ActivityState.None)
+            {
+                return;
+            }
+
             ChangeState(OnFinish, State == ActivityState.Executed ? ActivityState.Finished : State); // If relevant, preserve the previous state
 
             if (State == ActivityState.Finished)
Index: Core/Common/src/Core.Common.Gui/Forms/ProgressDialog/ActivityProgressDialog.cs
===================================================================
diff -u -r0be4ede909cda20598ffd400f452e08c99089bcb -rd24dba0f0c60fe14353ac3c5622e12a9d5bd758d
--- Core/Common/src/Core.Common.Gui/Forms/ProgressDialog/ActivityProgressDialog.cs	(.../ActivityProgressDialog.cs)	(revision 0be4ede909cda20598ffd400f452e08c99089bcb)
+++ Core/Common/src/Core.Common.Gui/Forms/ProgressDialog/ActivityProgressDialog.cs	(.../ActivityProgressDialog.cs)	(revision d24dba0f0c60fe14353ac3c5622e12a9d5bd758d)
@@ -157,8 +157,6 @@
 
         private void RunActivity(int stepNumberForProgressNotification, int activityCount)
         {
-            runningActivity.LogMessages.Clear();
-
             if (InvokeRequired)
             {
                 UpdateActivityStepControlsDelegate updateDelegate = UpdateProgressControls;
@@ -171,6 +169,8 @@
 
             try
             {
+                runningActivity.LogMessages.Clear();
+
                 if (RenderedMessageLogAppender.Instance != null)
                 {
                     RenderedMessageLogAppender.Instance.AppendMessageLineAction = message => runningActivity.LogMessages.Add(message);
Index: Core/Common/test/Core.Common.Base.Test/Service/ActivityTest.cs
===================================================================
diff -u -r67284323e2785c651633d9c52049ba12a9c70e6a -rd24dba0f0c60fe14353ac3c5622e12a9d5bd758d
--- Core/Common/test/Core.Common.Base.Test/Service/ActivityTest.cs	(.../ActivityTest.cs)	(revision 67284323e2785c651633d9c52049ba12a9c70e6a)
+++ Core/Common/test/Core.Common.Base.Test/Service/ActivityTest.cs	(.../ActivityTest.cs)	(revision d24dba0f0c60fe14353ac3c5622e12a9d5bd758d)
@@ -204,10 +204,10 @@
         }
 
         [Test]
-        public void Finish_SkippedActivityWithcSuccessfulFinish_MessageIsSendToLogAndPreviousStateIsPreserved()
+        public void Finish_SkippedActivityWithSuccessfulFinish_MessageIsSendToLogAndPreviousStateIsPreserved()
         {
             // Setup
-            var activity = new SimpleActivity(false, false, false, true);
+            var activity = new SimpleActivity(false, false, false, ActivityState.Skipped);
 
             activity.Run();
 
@@ -223,19 +223,30 @@
             Assert.AreEqual(ActivityState.Skipped, activity.State);
         }
 
+        [Test]
+        public void Finish_NoneActivityWithSuccessfulFinish_NoMessageIsSendToLogAndPreviousStateIsPreserved()
+        {
+            // Setup
+            var activity = new SimpleActivity(false, false, false, ActivityState.None);
+
+            // Call / Assert
+            TestHelper.AssertLogMessagesCount(() => activity.Finish(), 0);
+            Assert.AreEqual(ActivityState.None, activity.State);
+        }
+
         private class SimpleActivity : Activity
         {
             private readonly bool throwOnRun;
             private readonly bool throwOnCancel;
             private readonly bool throwOnFinish;
-            private readonly bool skipped;
+            private readonly ActivityState? specialStateAfterRun;
 
-            public SimpleActivity(bool throwOnRun, bool throwOnCancel, bool throwOnFinish, bool skipped = false)
+            public SimpleActivity(bool throwOnRun, bool throwOnCancel, bool throwOnFinish, ActivityState? specialStateAfterRun = null)
             {
                 this.throwOnRun = throwOnRun;
                 this.throwOnCancel = throwOnCancel;
                 this.throwOnFinish = throwOnFinish;
-                this.skipped = skipped;
+                this.specialStateAfterRun = specialStateAfterRun;
             }
 
             public void SetProgressText(string progressText)
@@ -245,9 +256,9 @@
 
             protected override void OnRun()
             {
-                if (skipped)
+                if (specialStateAfterRun != null)
                 {
-                    State = ActivityState.Skipped;
+                    State = (ActivityState) specialStateAfterRun;
                     return;
                 }