diff --git a/src/ZB.MOM.WW.MxGateway.Server/Workers/WorkerClient.cs b/src/ZB.MOM.WW.MxGateway.Server/Workers/WorkerClient.cs
index 0044abc..41cf7bf 100644
--- a/src/ZB.MOM.WW.MxGateway.Server/Workers/WorkerClient.cs
+++ b/src/ZB.MOM.WW.MxGateway.Server/Workers/WorkerClient.cs
@@ -950,6 +950,21 @@ public sealed class WorkerClient : IWorkerClient
         CancellationToken cancellationToken)
     {
         WorkerEnvelope envelope = await _reader.ReadAsync(cancellationToken).ConfigureAwait(false);
+
+        // IPC-35: a fault frame during the handshake is the worker reporting a structured startup
+        // failure — most often MXAccess COM creation (not installed, not registered, access denied)
+        // — not a protocol problem. Flattening it to ProtocolViolation discarded the category and
+        // diagnostic exactly where they matter most: first session open on a freshly deployed host,
+        // where the message reaches the operator log and the client's OpenFailed detail. Use the
+        // same formatter the steady-state fault path uses so both windows read alike.
+        if (envelope.BodyCase == WorkerEnvelope.BodyOneofCase.WorkerFault
+            && expectedBody != WorkerEnvelope.BodyOneofCase.WorkerFault)
+        {
+            throw new WorkerClientException(
+                WorkerClientErrorCode.WorkerFaulted,
+                CreateWorkerFaultMessage(envelope.WorkerFault));
+        }
+
         if (envelope.BodyCase != expectedBody)
         {
             throw new WorkerClientException(
diff --git a/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Workers/WorkerClientTests.cs b/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Workers/WorkerClientTests.cs
index eaab7e0..ad3761b 100644
--- a/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Workers/WorkerClientTests.cs
+++ b/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Workers/WorkerClientTests.cs
@@ -322,6 +322,45 @@ public sealed class WorkerClientTests
         }
     }
 
+    /// <summary>
+    ///     A <c>WorkerFault</c> arriving in place of a handshake frame is the worker reporting a
+    ///     structured startup failure — most often MXAccess COM creation — not a protocol problem, so
+    ///     the gateway surfaces <see cref="WorkerClientErrorCode.WorkerFaulted"/> with the fault's
+    ///     category and diagnostic rather than a generic protocol violation naming only the body type
+    ///     (IPC-35). This is the window where the information matters most: first session open on a
+    ///     freshly deployed host, where the message reaches the operator log and the client's
+    ///     <c>OpenFailed</c> detail.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task StartAsync_WhenWorkerFaultsDuringHandshake_SurfacesFaultCategoryAndDiagnostic()
+    {
+        const string diagnostic = "CoCreateInstance for LMXProxy.LMXProxyServer.1 failed (0x80040154).";
+
+        await using FakeWorkerHarness harness = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = harness.CreateClient();
+
+        Task startTask = client.StartAsync(CancellationToken.None);
+
+        WorkerEnvelope gatewayHello = await harness.ReadGatewayEnvelopeAsync().WaitAsync(TestTimeout);
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.GatewayHello, gatewayHello.BodyCase);
+
+        // The hello succeeds; the fault replaces the WorkerReady, which is where a COM creation
+        // failure actually lands (the worker creates MXAccess after answering the hello).
+        await harness.SendWorkerHelloAsync();
+        await harness.EmitFaultAsync(WorkerFaultCategory.MxaccessCreationFailed, diagnostic);
+
+        WorkerClientException exception = await Assert.ThrowsAsync<WorkerClientException>(
+            async () => await startTask.WaitAsync(TestTimeout));
+
+        Assert.Equal(WorkerClientErrorCode.WorkerFaulted, exception.ErrorCode);
+        Assert.Contains(
+            WorkerFaultCategory.MxaccessCreationFailed.ToString(),
+            exception.Message,
+            StringComparison.Ordinal);
+        Assert.Contains(diagnostic, exception.Message, StringComparison.Ordinal);
+    }
+
     /// <summary>
     ///     The envelope <c>sequence</c> is a monotonic per-sender counter (gateway.md), so the values
     ///     observed on the pipe must be strictly increasing in wire order. Stamping the sequence when