Clear pending Python error when a Try-style conversion fails

src/embed_tests/TestPyObject.cs

@@ -102,6 +102,40 @@ public void InheritedMethodsAutoacquireGIL()
         {
             PythonEngine.Exec("from System import String\nString.Format('{0},{1}', 1, 2)");
         }
+
+        [Test]
+        public void FailedTryAsDoesNotLeavePythonErrorSet()
+        {
+            using var _ = Py.GIL();
+
+            using var locals = new PyDict();
+            PythonEngine.Exec("def a_function(a, b): return a * b", null, locals);
+            using var pyObject = locals.GetItem("a_function");
+
+            Assert.IsFalse(pyObject.TryAs<int>(out var _));
+            Assert.IsFalse(Exceptions.ErrorOccurred());
+
+            Assert.IsFalse(pyObject.TryAsManagedObject(typeof(decimal), out var _));
+            Assert.IsFalse(Exceptions.ErrorOccurred());
+
+            // The thread state must be clean for subsequent unrelated Python calls
+            Assert.DoesNotThrow(() => PyModule.FromString("TryAsLeakCheck", "x = 1").Dispose());
+        }
+
+        [Test]
+        public void FailedAsManagedObjectRaisesWithConversionErrorAsCause()
+        {
+            using var _ = Py.GIL();
+
+            using var locals = new PyDict();
+            PythonEngine.Exec("def a_function(a, b): return a * b", null, locals);
+            using var pyObject = locals.GetItem("a_function");
+
+            var exception = Assert.Throws<InvalidCastException>(() => pyObject.AsManagedObject(typeof(int)));
+            Assert.IsNotNull(exception.InnerException);
+            StringAssert.Contains("int()", exception.InnerException.Message);
+            Assert.IsFalse(Exceptions.ErrorOccurred());
+        }
     }
 
     public class PyObjectTestMethods

src/perf_tests/Python.PerformanceTests.csproj

@@ -13,7 +13,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.*" />
-    <PackageReference Include="quantconnect.pythonnet" Version="2.0.62" GeneratePathProperty="true">
+    <PackageReference Include="quantconnect.pythonnet" Version="2.0.63" GeneratePathProperty="true">
       <IncludeAssets>compile</IncludeAssets>
     </PackageReference>
   </ItemGroup>
@@ -25,7 +25,7 @@
   </Target>
 
   <Target Name="CopyBaseline" AfterTargets="Build">
-    <Copy SourceFiles="$(NuGetPackageRoot)quantconnect.pythonnet\2.0.62\lib\net10.0\Python.Runtime.dll" DestinationFolder="$(OutDir)baseline" />
+    <Copy SourceFiles="$(NuGetPackageRoot)quantconnect.pythonnet\2.0.63\lib\net10.0\Python.Runtime.dll" DestinationFolder="$(OutDir)baseline" />
   </Target>
 
   <Target Name="CopyNewBuild" AfterTargets="Build">

src/runtime/Properties/AssemblyInfo.cs

@@ -4,5 +4,5 @@
 [assembly: InternalsVisibleTo("Python.EmbeddingTest, PublicKey=00240000048000009400000006020000002400005253413100040000110000005ffd8f49fb44ab0641b3fd8d55e749f716e6dd901032295db641eb98ee46063cbe0d4a1d121ef0bc2af95f8a7438d7a80a3531316e6b75c2dae92fb05a99f03bf7e0c03980e1c3cfb74ba690aca2f3339ef329313bcc5dccced125a4ffdc4531dcef914602cd5878dc5fbb4d4c73ddfbc133f840231343e013762884d6143189")]
 [assembly: InternalsVisibleTo("Python.Test, PublicKey=00240000048000009400000006020000002400005253413100040000110000005ffd8f49fb44ab0641b3fd8d55e749f716e6dd901032295db641eb98ee46063cbe0d4a1d121ef0bc2af95f8a7438d7a80a3531316e6b75c2dae92fb05a99f03bf7e0c03980e1c3cfb74ba690aca2f3339ef329313bcc5dccced125a4ffdc4531dcef914602cd5878dc5fbb4d4c73ddfbc133f840231343e013762884d6143189")]
 
-[assembly: AssemblyVersion("2.0.62")]
-[assembly: AssemblyFileVersion("2.0.62")]
+[assembly: AssemblyVersion("2.0.63")]
+[assembly: AssemblyFileVersion("2.0.63")]

src/runtime/Python.Runtime.csproj

@@ -5,7 +5,7 @@
     <RootNamespace>Python.Runtime</RootNamespace>
     <AssemblyName>Python.Runtime</AssemblyName>
     <PackageId>QuantConnect.pythonnet</PackageId>
-    <Version>2.0.62</Version>
+    <Version>2.0.63</Version>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <RepositoryUrl>https://github.com/pythonnet/pythonnet</RepositoryUrl>

src/runtime/PythonTypes/PyObject.cs

@@ -169,7 +169,7 @@ public static PyObject FromManagedObject(object ob)
         /// </remarks>
         public object? AsManagedObject(Type t)
         {
-            if (!TryAsManagedObject(t, out var result))
+            if (!Converter.ToManaged(obj, t, out var result, setError: true))
             {
                 throw new InvalidCastException("cannot convert object to target type",
                     PythonException.FetchCurrentOrNull(out _));
@@ -188,7 +188,15 @@ public static PyObject FromManagedObject(object ob)
         /// </summary>
         public bool TryAsManagedObject(Type t, out object? result)
         {
-            return Converter.ToManaged(obj, t, out result, true);
+            if (Converter.ToManaged(obj, t, out result, setError: false))
+            {
+                return true;
+            }
+            // A failed Try-conversion must not leave a Python error pending on the
+            // thread: the caller only sees the boolean, so a stale error indicator
+            // would surface from an unrelated later call on this thread.
+            Exceptions.Clear();
+            return false;
         }
 
         /// <summary>