diff --git a/src/Aquarium.Engine/AquariumHost.cs b/src/Aquarium.Engine/AquariumHost.cs
index 104af9e..f3c1864 100644
--- a/src/Aquarium.Engine/AquariumHost.cs
+++ b/src/Aquarium.Engine/AquariumHost.cs
@@ -28,7 +28,7 @@ public static class AquariumHost
         catch (Exception error)
         {
             // Startup refusals carry raw, attacker-writable paths; the console gets them escaped, once, here.
-            Console.Error.WriteLine($"Client runtime failed to start. {ClientRuntimeLoader.Printable(error.Message)}");
+            Console.Error.WriteLine($"Client runtime failed to start ({ClientRuntimeLoader.Printable(error.GetType().FullName ?? error.GetType().Name)}). {ClientRuntimeLoader.Printable(error.Message)}");
             loader?.Dispose();
             return 1;
         }
diff --git a/tests/Aquarium.Engine.Tests/ClientRuntimeLoaderTrustTests.cs b/tests/Aquarium.Engine.Tests/ClientRuntimeLoaderTrustTests.cs
index f3a6b46..6ab1693 100644
--- a/tests/Aquarium.Engine.Tests/ClientRuntimeLoaderTrustTests.cs
+++ b/tests/Aquarium.Engine.Tests/ClientRuntimeLoaderTrustTests.cs
@@ -77,6 +77,8 @@ public sealed class ClientRuntimeLoaderTrustTests : IDisposable
                 Thread.Sleep(100);
             }
         }
+
+        Console.Error.WriteLine($"Warning: test cleanup could not delete (locked loaded assembly?): {ClientRuntimeLoader.Printable(work)}");
     }
 
     // A real client assembly: the minimal sample, copied so its location is ours to choose.
@@ -389,7 +391,7 @@ public sealed class ClientRuntimeLoaderTrustTests : IDisposable
         var errors = CaptureError(() => exit = AquariumHost.Run(["--headless", "--client-trusted-root", volumeRoot]));
 
         Assert.Equal(1, exit);
-        Assert.Contains("Client runtime failed to start.", errors);
+        Assert.Contains("Client runtime failed to start (System.ArgumentException).", errors);
         Assert.Contains("cannot be the client runtime trusted root", errors);
     }