diff --git a/src/Http.Tests/RequestActivityEventSourceTests.cs b/src/Http.Tests/RequestActivityEventSourceTests.cs
index 7326045..3cbb08a 100644
--- a/src/Http.Tests/RequestActivityEventSourceTests.cs
+++ b/src/Http.Tests/RequestActivityEventSourceTests.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics.Tracing;
 using System.Linq;
 using Thor.Analyzer;
@@ -242,6 +243,34 @@ public void Stop_HttpResponse_Null()
 
         #endregion
 
+        #region Outer Activity Warning
+
+        [Fact(DisplayName = "OuterActivityNotAllowed: Should log a outer activity is not allowed")]
+        public void OuterActivityNotAllowed()
+        {
+            RequestActivityEventSource.Log.Listen((listener) =>
+            {
+                // arrange
+                const string expectedMessage = "Outer activities are not allowed when creating a server-side message activity.";
+                Guid activityId = Guid.NewGuid();
+
+                // act
+                RequestActivityEventSource.Log.OuterActivityNotAllowed(activityId);
+
+                // assert
+                TelemetryEvent firstItem = listener
+                    .OrderedEvents
+                    .Select(e => e.Map("7778"))
+                    .FirstOrDefault(e => e.Message == expectedMessage);
+
+                Assert.NotNull(firstItem);
+                Assert.Equal(EventLevel.Warning, firstItem.Level);
+                AssertItem(firstItem, 0, activityId, expectedMessage);
+            });
+        }
+
+        #endregion
+
         #region Begin/End Transfer Events
 
         [Fact(DisplayName = "BeginTransfer: Should log a begin transfer")]
@@ -296,6 +325,44 @@ public void EndTransfer()
 
         #endregion
 
+        #region Internal Server Error
+
+        [Fact(DisplayName = "InternalServerErrorOccurred: Should log a internal server error exception")]
+        public void InternalServerErrorOccurred()
+        {
+            RequestActivityEventSource.Log.Listen((listener) =>
+            {
+                // arrange
+                ConcurrentQueue<AttachmentDescriptor> attachments = new ConcurrentQueue<AttachmentDescriptor>();
+                const string expectedMessage = "Internal server error occurred.";
+                Exception exception = new Exception();
+                AttachmentDispatcher.Instance.Attach(d => attachments.Enqueue(d));
+
+                // act
+                RequestActivityEventSource.Log.InternalServerErrorOccurred(exception);
+
+                // assert
+                AttachmentDispatcher.Instance.Detach(d => attachments.Enqueue(d));
+                TelemetryEvent firstItem = listener
+                    .OrderedEvents
+                    .Select(e => e.Map("7779"))
+                    .FirstOrDefault(e => e.Message == expectedMessage);
+
+                Assert.NotNull(firstItem);
+                Assert.Equal(EventLevel.Error, firstItem.Level);
+                AssertItem(firstItem, 0, Guid.Empty, expectedMessage);
+                Assert.Collection(attachments,
+                    d =>
+                    {
+                        Assert.Matches("^\\d{8}\\-[a-f\\d]{32}$", d.Id);
+                        Assert.Equal("exception", d.Name);
+                        Assert.Equal(nameof(Exception), d.TypeName);
+                    });
+            });
+        }
+
+        #endregion
+
         private static void AssertItem(TelemetryEvent item, int expectedCount,
             Guid expectedActivityId, Guid? expectedUserId, string expectedMessage)
         {
diff --git a/src/Http/RequestActivityEventSource.cs b/src/Http/RequestActivityEventSource.cs
index 25fb9e4..dc164cb 100644
--- a/src/Http/RequestActivityEventSource.cs
+++ b/src/Http/RequestActivityEventSource.cs
@@ -15,6 +15,7 @@ internal sealed class RequestActivityEventSource
         private const int _beginTransferEventId = 5;
         private const int _endTransferEventId = 6;
         private const int _outerActivityWarningEventId = 7;
+        private const int _internalServerErrorEventId = 8;
 
         public static RequestActivityEventSource Log { get; } = new RequestActivityEventSource();
 
@@ -143,7 +144,8 @@ private void Stop(int applicationId, Guid activityId, Guid userId, int statusCod
         #region Outer Activity Warning
 
         /// <summary>
-        /// A warning regarding outer activities which were not allowed when opening a new server-side message activity.
+        /// A warning regarding outer activities which are not allowed when opening a new
+        /// server-side message activity.
         /// </summary>
         [NonEvent]
         public void OuterActivityNotAllowed(Guid activityId)
@@ -201,6 +203,58 @@ private void EndTransfer(Guid relatedActivityId, int applicationId, Guid activit
 
         #endregion
 
+        #region Internal Server Error
+
+        /// <summary>
+        /// A internal server error occurred during request/response processing.
+        /// </summary>
+        [NonEvent]
+        public void InternalServerErrorOccurred(Exception exception)
+        {
+            if (IsEnabled())
+            {
+                AttachmentId attachmentId = AttachmentId.NewId();
+                ExceptionAttachment attachment = AttachmentFactory.Create(attachmentId,
+                    nameof(exception), exception);
+
+                AttachmentDispatcher.Instance.Dispatch(attachment);
+                InternalServerErrorOccurred(Application.Id, ActivityStack.Id, attachmentId);
+            }
+        }
+
+        [Event(_internalServerErrorEventId, Level = EventLevel.Error,
+            Message = "Internal server error occurred.", Version = 1)]
+        private void InternalServerErrorOccurred(int applicationId, Guid activityId,
+            string attachmentId)
+        {
+            InternalServerErrorOccurredCore(_internalServerErrorEventId, applicationId, activityId,
+                attachmentId);
+        }
+
+        [NonEvent]
+        private unsafe void InternalServerErrorOccurredCore(int eventId, int applicationId,
+            Guid activityId, string attachmentId)
+        {
+            StringExtensions.SetToEmptyIfNull(ref attachmentId);
+
+            fixed (char* attachmentIdBytes = attachmentId)
+            {
+                const short dataCount = 3;
+                EventData* data = stackalloc EventData[dataCount];
+
+                data[0].DataPointer = (IntPtr)(&applicationId);
+                data[0].Size = 4;
+                data[1].DataPointer = (IntPtr)(&activityId);
+                data[1].Size = 16;
+                data[2].DataPointer = (IntPtr)attachmentIdBytes;
+                data[2].Size = ((attachmentId.Length + 1) * 2);
+
+                WriteEventCore(eventId, dataCount, data);
+            }
+        }
+
+        #endregion
+
         #region Tasks and Opcodes
 
         public static class Tasks