diff --git a/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs b/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs
index 69bc7bef13336..febbf3cd043e9 100644
--- a/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs
+++ b/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs
@@ -335,7 +335,7 @@ public async Task RequestSentResponseDisposed_ThrowsOnServer()
 
                 Stopwatch sw = Stopwatch.StartNew();
                 bool hasFailed = false;
-                while (sw.Elapsed < TestHelper.PassingTestTimeout)
+                while (sw.Elapsed < TimeSpan.FromSeconds(15))
                 {
                     try
                     {
@@ -371,6 +371,7 @@ public async Task RequestSentResponseDisposed_ThrowsOnServer()
 
                 // We haven't finished reading the whole respose, but we're disposing it, which should turn into an exception on the server-side.
                 response.Dispose();
+                await serverTask;
             });
 
             await new[] { clientTask, serverTask }.WhenAllOrAnyFailed(20_000);
@@ -392,7 +393,7 @@ public async Task RequestSendingResponseDisposed_ThrowsOnServer()
 
                 Stopwatch sw = Stopwatch.StartNew();
                 bool hasFailed = false;
-                while (sw.Elapsed < TestHelper.PassingTestTimeout)
+                while (sw.Elapsed < TimeSpan.FromSeconds(15))
                 {
                     try
                     {
@@ -425,6 +426,7 @@ public async Task RequestSendingResponseDisposed_ThrowsOnServer()
 
                 // We haven't finished sending the whole request, but we're disposing the response, which should turn into an exception on the server-side.
                 response.Dispose();
+                await serverTask;
             });
 
             await new[] { clientTask, serverTask }.WhenAllOrAnyFailed(20_000);
@@ -996,7 +998,7 @@ public async Task StatusCodes_ReceiveSuccess(HttpStatusCode statusCode, bool qpa
                 VersionPolicy = HttpVersionPolicy.RequestVersionExact
             };
             HttpResponseMessage response = await client.SendAsync(request).WaitAsync(TimeSpan.FromSeconds(10));
-            
+
             Assert.Equal(statusCode, response.StatusCode);
 
             await serverTask;
diff --git a/src/libraries/System.Net.Quic/src/System/Net/Quic/Implementations/MsQuic/MsQuicStream.cs b/src/libraries/System.Net.Quic/src/System/Net/Quic/Implementations/MsQuic/MsQuicStream.cs
index bbaf9c4ed41bb..827029a3b74f5 100644
--- a/src/libraries/System.Net.Quic/src/System/Net/Quic/Implementations/MsQuic/MsQuicStream.cs
+++ b/src/libraries/System.Net.Quic/src/System/Net/Quic/Implementations/MsQuic/MsQuicStream.cs
@@ -265,7 +265,7 @@ internal override async ValueTask WriteAsync(ReadOnlySequence<byte> buffers, boo
         {
             ThrowIfDisposed();
 
-            using CancellationTokenRegistration registration = HandleWriteStartState(cancellationToken);
+            using CancellationTokenRegistration registration = HandleWriteStartState(buffers.IsEmpty, cancellationToken);
 
             await SendReadOnlySequenceAsync(buffers, endStream ? QUIC_SEND_FLAGS.FIN : QUIC_SEND_FLAGS.NONE).ConfigureAwait(false);
 
@@ -281,7 +281,7 @@ internal override async ValueTask WriteAsync(ReadOnlyMemory<ReadOnlyMemory<byte>
         {
             ThrowIfDisposed();
 
-            using CancellationTokenRegistration registration = HandleWriteStartState(cancellationToken);
+            using CancellationTokenRegistration registration = HandleWriteStartState(buffers.IsEmpty, cancellationToken);
 
             await SendReadOnlyMemoryListAsync(buffers, endStream ? QUIC_SEND_FLAGS.FIN : QUIC_SEND_FLAGS.NONE).ConfigureAwait(false);
 
@@ -292,20 +292,20 @@ internal override async ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, bool e
         {
             ThrowIfDisposed();
 
-            using CancellationTokenRegistration registration = HandleWriteStartState(cancellationToken);
+            using CancellationTokenRegistration registration = HandleWriteStartState(buffer.IsEmpty, cancellationToken);
 
             await SendReadOnlyMemoryAsync(buffer, endStream ? QUIC_SEND_FLAGS.FIN : QUIC_SEND_FLAGS.NONE).ConfigureAwait(false);
 
             HandleWriteCompletedState();
         }
 
-        private CancellationTokenRegistration HandleWriteStartState(CancellationToken cancellationToken)
+        private CancellationTokenRegistration HandleWriteStartState(bool emptyBuffer, CancellationToken cancellationToken)
         {
             if (_state.SendState == SendState.Closed)
             {
                 throw new InvalidOperationException(SR.net_quic_writing_notallowed);
             }
-            else if ( _state.SendState == SendState.Aborted)
+            if (_state.SendState == SendState.Aborted)
             {
                 if (_state.SendErrorCode != -1)
                 {
@@ -363,10 +363,14 @@ private CancellationTokenRegistration HandleWriteStartState(CancellationToken ca
 
                     throw new OperationCanceledException(SR.net_quic_sending_aborted);
                 }
-                else if (_state.SendState == SendState.ConnectionClosed)
+                if (_state.SendState == SendState.ConnectionClosed)
                 {
                     throw GetConnectionAbortedException(_state);
                 }
+
+                // Change the state in the same lock where we check for final states to prevent coming back from Aborted/ConnectionClosed.
+                Debug.Assert(_state.SendState != SendState.Pending);
+                _state.SendState = emptyBuffer ? SendState.Finished : SendState.Pending;
             }
 
             return registration;
@@ -632,7 +636,10 @@ internal override void Shutdown()
 
             lock (_state)
             {
-                _state.SendState = SendState.Finished;
+                if (_state.SendState < SendState.Finished)
+                {
+                    _state.SendState = SendState.Finished;
+                }
             }
 
             // it is ok to send shutdown several times, MsQuic will ignore it
@@ -1157,12 +1164,6 @@ private unsafe ValueTask SendReadOnlyMemoryAsync(
            ReadOnlyMemory<byte> buffer,
            QUIC_SEND_FLAGS flags)
         {
-            lock (_state)
-            {
-                Debug.Assert(_state.SendState != SendState.Pending);
-                _state.SendState = buffer.IsEmpty ? SendState.Finished : SendState.Pending;
-            }
-
             if (buffer.IsEmpty)
             {
                 if ((flags & QUIC_SEND_FLAGS.FIN) == QUIC_SEND_FLAGS.FIN)
@@ -1211,13 +1212,6 @@ private unsafe ValueTask SendReadOnlySequenceAsync(
            ReadOnlySequence<byte> buffers,
            QUIC_SEND_FLAGS flags)
         {
-
-            lock (_state)
-            {
-                Debug.Assert(_state.SendState != SendState.Pending);
-                _state.SendState = buffers.IsEmpty ? SendState.Finished : SendState.Pending;
-            }
-
             if (buffers.IsEmpty)
             {
                 if ((flags & QUIC_SEND_FLAGS.FIN) == QUIC_SEND_FLAGS.FIN)
@@ -1281,12 +1275,6 @@ private unsafe ValueTask SendReadOnlyMemoryListAsync(
            ReadOnlyMemory<ReadOnlyMemory<byte>> buffers,
            QUIC_SEND_FLAGS flags)
         {
-            lock (_state)
-            {
-                Debug.Assert(_state.SendState != SendState.Pending);
-                _state.SendState = buffers.IsEmpty ? SendState.Finished : SendState.Pending;
-            }
-
             if (buffers.IsEmpty)
             {
                 if ((flags & QUIC_SEND_FLAGS.FIN) == QUIC_SEND_FLAGS.FIN)