diff --git a/src/Microsoft.TestPlatform.TestHostProvider/Hosting/DotnetTestHostManager.cs b/src/Microsoft.TestPlatform.TestHostProvider/Hosting/DotnetTestHostManager.cs
index 630149957a..7b21892200 100644
--- a/src/Microsoft.TestPlatform.TestHostProvider/Hosting/DotnetTestHostManager.cs
+++ b/src/Microsoft.TestPlatform.TestHostProvider/Hosting/DotnetTestHostManager.cs
@@ -955,34 +955,43 @@ private string GetTestHostPath(string runtimeConfigDevPath, string depsFilePath,
                 {
 #if NETCOREAPP
                     using var doc = JsonDocument.Parse(stream);
-                    var runtimeOptions = doc.RootElement.GetProperty("runtimeOptions");
-                    var additionalProbingPaths = runtimeOptions.GetProperty("additionalProbingPaths");
-                    foreach (var x in additionalProbingPaths.EnumerateArray())
+
+                    if (doc.RootElement.TryGetProperty("runtimeOptions", out var runtimeOptions) &&
+                        runtimeOptions.TryGetProperty("additionalProbingPaths", out var additionalProbingPaths))
                     {
-                        EqtTrace.Verbose("DotnetTestHostmanager: Looking for path {0} in folder {1}", testHostPath, x.GetString());
-                        string testHostFullPath;
-                        try
-                        {
-                            testHostFullPath = Path.Combine(x.GetString()!, testHostPath);
-                        }
-                        catch (ArgumentException)
+                        foreach (var x in additionalProbingPaths.EnumerateArray())
                         {
-                            // https://github.com/Microsoft/vstest/issues/847
-                            // skip any invalid paths and continue checking the others
-                            continue;
-                        }
+                            EqtTrace.Verbose("DotnetTestHostmanager: Looking for path {0} in folder {1}", testHostPath, x.GetString());
+                            string testHostFullPath;
+                            try
+                            {
+                                testHostFullPath = Path.Combine(x.GetString()!, testHostPath);
+                            }
+                            catch (ArgumentException)
+                            {
+                                // https://github.com/Microsoft/vstest/issues/847
+                                // skip any invalid paths and continue checking the others
+                                continue;
+                            }
 
-                        if (_fileHelper.Exists(testHostFullPath))
-                        {
-                            EqtTrace.Verbose("DotnetTestHostmanager: Found testhost.dll in {0}", testHostFullPath);
-                            return testHostFullPath;
+                            if (_fileHelper.Exists(testHostFullPath))
+                            {
+                                EqtTrace.Verbose("DotnetTestHostmanager: Found testhost.dll in {0}", testHostFullPath);
+                                return testHostFullPath;
+                            }
                         }
                     }
 #else
                     using var reader = new StreamReader(stream);
                     var parsed = Json.Deserialize(reader) as IDictionary<string, object>;
-                    var runtimeOpts = parsed?["runtimeOptions"] as IDictionary<string, object>;
-                    var probingPaths = runtimeOpts?["additionalProbingPaths"] as IList<object>;
+                    var runtimeOpts = parsed is not null && parsed.TryGetValue("runtimeOptions", out var runtimeOptsObj)
+                        ? runtimeOptsObj as IDictionary<string, object>
+                        : null;
+
+                    var probingPaths = runtimeOpts is not null && runtimeOpts.TryGetValue("additionalProbingPaths", out var probingPathsObj)
+                        ? probingPathsObj as IList<object>
+                        : null;
+
                     if (probingPaths is not null)
                     {
                         foreach (var x in probingPaths)
diff --git a/test/Microsoft.TestPlatform.TestHostProvider.UnitTests/Hosting/DotnetTestHostManagerFilesystemIntegrationTests.cs b/test/Microsoft.TestPlatform.TestHostProvider.UnitTests/Hosting/DotnetTestHostManagerFilesystemIntegrationTests.cs
index 7226c3d4f7..27bb05c09a 100644
--- a/test/Microsoft.TestPlatform.TestHostProvider.UnitTests/Hosting/DotnetTestHostManagerFilesystemIntegrationTests.cs
+++ b/test/Microsoft.TestPlatform.TestHostProvider.UnitTests/Hosting/DotnetTestHostManagerFilesystemIntegrationTests.cs
@@ -153,6 +153,56 @@ public void GetTestHostProcessStartInfo_FindsTestHostDllViaRealDepsJsonAndRuntim
             startInfo.Arguments.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar));
     }
 
+    [TestMethod]
+    public void GetTestHostProcessStartInfo_DoesNotThrowWhenRuntimeConfigDevJsonHasNoAdditionalProbingPaths()
+    {
+        // Arrange — a runtimeconfig.dev.json that exists but only carries runtime options other than
+        // additionalProbingPaths (for example Hot Reload switches generated by the SDK for net6.0+ Debug builds).
+        // The manager must not fail reading it; it should fall back to finding testhost.dll next to the source.
+        string sourceDll = Path.Combine(_tempDir, "TestProject.dll");
+        string depsJsonPath = Path.Combine(_tempDir, "TestProject.deps.json");
+
+        File.WriteAllText(sourceDll, "fake test dll");
+
+        // Minimal deps.json — testhost not in it, so resolution falls through to the source directory.
+        string depsJson = """
+            {
+                "runtimeTarget": { "name": ".NETCoreApp,Version=v8.0" },
+                "compilationOptions": {},
+                "targets": { ".NETCoreApp,Version=v8.0": {} },
+                "libraries": {}
+            }
+            """;
+        File.WriteAllText(depsJsonPath, depsJson);
+
+        // runtimeconfig.dev.json without an "additionalProbingPaths" property.
+        string runtimeConfigDevJson = """
+            {
+                "runtimeOptions": {
+                    "configProperties": {
+                        "System.Reflection.Metadata.MetadataUpdater.IsSupported": true,
+                        "System.StartupHookProvider.IsSupported": true
+                    }
+                }
+            }
+            """;
+        File.WriteAllText(Path.Combine(_tempDir, "TestProject.runtimeconfig.dev.json"), runtimeConfigDevJson);
+
+        // Place testhost.dll next to source so the manager can resolve it without probing paths.
+        string testhostNextToSource = Path.Combine(_tempDir, "testhost.dll");
+        File.WriteAllText(testhostNextToSource, "fake testhost");
+
+        var manager = CreateManager(new FileHelper());
+        manager.Initialize(_mockMessageLogger.Object, "<RunSettings><RunConfiguration><TargetFrameworkVersion>.NETCoreApp,Version=v8.0</TargetFrameworkVersion></RunConfiguration></RunSettings>");
+
+        // Act — this previously threw KeyNotFoundException when additionalProbingPaths was missing.
+        var startInfo = manager.GetTestHostProcessStartInfo(new[] { sourceDll }, null, _connectionInfo);
+
+        // Assert — resolution succeeds and falls back to testhost.dll next to the source.
+        Assert.IsNotNull(startInfo.Arguments);
+        Assert.Contains("testhost.dll", startInfo.Arguments);
+    }
+
     [TestMethod]
     public void GetTestHostProcessStartInfo_PassesDepsFileArgWhenDepsJsonExists()
     {