diff --git a/Src/IronPythonTest/Cases/CPythonCases.cs b/Src/IronPythonTest/Cases/CPythonCases.cs
index d99e77721..eb08df983 100644
--- a/Src/IronPythonTest/Cases/CPythonCases.cs
+++ b/Src/IronPythonTest/Cases/CPythonCases.cs
@@ -27,7 +27,14 @@ public int StandardCPythonTests(TestInfo testcase) {
                 TestContext.Progress.WriteLine(testcase.Name); // should be printed immediately
                 return executor.RunTest(testcase);
             } catch (Exception e) {
-                Assert.Fail(executor.FormatException(e));
+                if(e is AggregateException ae) {
+                    ae.Handle((x) => {
+                       Assert.Fail(executor.FormatException(x));
+                       return true; 
+                    });
+                } else {
+                    Assert.Fail(executor.FormatException(e));
+                }
                 return -1;
             }
         }
@@ -48,7 +55,14 @@ public int AllCPythonTests(TestInfo testcase) {
                 TestContext.Progress.WriteLine(testcase.Name); // should be printed immediately
                 return executor.RunTest(testcase);
             } catch (Exception e) {
-                Assert.Fail(executor.FormatException(e));
+                if(e is AggregateException ae) {
+                    ae.Handle((x) => {
+                       Assert.Fail(executor.FormatException(x));
+                       return true; 
+                    });
+                } else {
+                    Assert.Fail(executor.FormatException(e));
+                }
                 return -1;
             }
         }
@@ -69,7 +83,14 @@ public int CTypesCPythonTests(TestInfo testcase) {
                 TestContext.Progress.WriteLine(testcase.Name); // should be printed immediately
                 return executor.RunTest(testcase);
             } catch (Exception e) {
-                Assert.Fail(executor.FormatException(e));
+                if(e is AggregateException ae) {
+                    ae.Handle((x) => {
+                       Assert.Fail(executor.FormatException(x));
+                       return true; 
+                    });
+                } else {
+                    Assert.Fail(executor.FormatException(e));
+                }
                 return -1;
             }
         }
diff --git a/Src/IronPythonTest/Cases/CaseExecuter.cs b/Src/IronPythonTest/Cases/CaseExecuter.cs
index 86fb93b35..7f702c682 100644
--- a/Src/IronPythonTest/Cases/CaseExecuter.cs
+++ b/Src/IronPythonTest/Cases/CaseExecuter.cs
@@ -258,24 +258,15 @@ private int GetResult(TestInfo testcase, ScriptEngine engine, ScriptSource sourc
                 engine.GetSysModule().SetVariable("argv", List.FromArrayNoCopy(new object[] { source.Path }));
                 var compiledCode = source.Compile(new IronPython.Compiler.PythonCompilerOptions() { ModuleName = "__main__" });
                 
-                var thread = new Thread(() => {
+                var task = Task<int>.Run(() => {
                     try {
-                        res = engine.Operations.ConvertTo<int>(compiledCode.Execute(scope) ?? 0);
+                        return engine.Operations.ConvertTo<int>(compiledCode.Execute(scope) ?? 0);
                     } catch (SystemExitException ex) {
-                        res = ex.GetExitCode(out object otherCode);
-                    } catch (ThreadAbortException) {
-                        Thread.ResetAbort();
-                    }
-                }) {
-                    IsBackground = true
-                };
-
-                thread.Start();
-
-                if (!thread.Join(testcase.Options.Timeout)) {
-                    if(!ClrModule.IsNetCoreApp) {
-                        thread.Abort();
+                        return ex.GetExitCode(out object otherCode);
                     }
+                });
+                
+                if (!task.Wait(testcase.Options.Timeout)) {
                     NUnit.Framework.TestContext.Error.WriteLine($"{testcase.Name} timed out after {testcase.Options.Timeout / 1000.0} seconds.");
                     res = -1;
                 }
diff --git a/Src/IronPythonTest/Cases/IronPythonCases.cs b/Src/IronPythonTest/Cases/IronPythonCases.cs
index 0cb823d23..7d5bbf3b7 100644
--- a/Src/IronPythonTest/Cases/IronPythonCases.cs
+++ b/Src/IronPythonTest/Cases/IronPythonCases.cs
@@ -21,7 +21,14 @@ public int IronPythonTests(TestInfo testcase) {
                 TestContext.Progress.WriteLine(testcase.Name);
                 return this.executor.RunTest(testcase);
             } catch (Exception e) {
-                Assert.Fail(this.executor.FormatException(e));
+                if(e is AggregateException ae) {
+                    ae.Handle((x) => {
+                       Assert.Fail(executor.FormatException(x));
+                       return true; 
+                    });
+                } else {
+                    Assert.Fail(this.executor.FormatException(e));
+                }
                 return -1;
             }
         }