try this for testing.

shell/platform/windows/flutter_windows_engine.cc

@@ -378,7 +378,12 @@ bool FlutterWindowsEngine::Run(std::string_view entrypoint) {
   FlutterRendererConfig renderer_config;
 
   if (enable_impeller_) {
-    // Impeller does not support a Software backend. Avoid failling back and
+    if (!surface_manager_) {
+      FML_LOG(ERROR) << "Could not create surface manager. Impeller backend "
+                        "does not support software rendering.";
+      return false;
+    }
+    // Impeller does not support a Software backend. Avoid falling back and
     // confusing the engine on which renderer is selected.
     renderer_config = GetOpenGLRendererConfig();
   } else {

shell/platform/windows/flutter_windows_engine_unittests.cc

@@ -223,6 +223,41 @@ TEST_F(FlutterWindowsEngineTest, RunWithoutANGLEUsesSoftware) {
   modifier.embedder_api().Shutdown = [](auto engine) { return kSuccess; };
 }
 
+TEST_F(FlutterWindowsEngineTest, RunWithoutANGLEOnImpellerFailsToStart) {
+  FlutterWindowsEngineBuilder builder{GetContext()};
+  builder.SetSwitches({"--enable-impeller"});
+  std::unique_ptr<FlutterWindowsEngine> engine = builder.Build();
+  EngineModifier modifier(engine.get());
+
+  modifier.embedder_api().NotifyDisplayUpdate =
+      MOCK_ENGINE_PROC(NotifyDisplayUpdate,
+                       ([engine_instance = engine.get()](
+                            FLUTTER_API_SYMBOL(FlutterEngine) raw_engine,
+                            const FlutterEngineDisplaysUpdateType update_type,
+                            const FlutterEngineDisplay* embedder_displays,
+                            size_t display_count) { return kSuccess; }));
+
+  // Accessibility updates must do nothing when the embedder engine is mocked
+  modifier.embedder_api().UpdateAccessibilityFeatures = MOCK_ENGINE_PROC(
+      UpdateAccessibilityFeatures,
+      [](FLUTTER_API_SYMBOL(FlutterEngine) engine,
+         FlutterAccessibilityFeature flags) { return kSuccess; });
+
+  // Stub out UpdateLocales and SendPlatformMessage as we don't have a fully
+  // initialized engine instance.
+  modifier.embedder_api().UpdateLocales = MOCK_ENGINE_PROC(
+      UpdateLocales, ([](auto engine, const FlutterLocale** locales,
+                         size_t locales_count) { return kSuccess; }));
+  modifier.embedder_api().SendPlatformMessage =
+      MOCK_ENGINE_PROC(SendPlatformMessage,
+                       ([](auto engine, auto message) { return kSuccess; }));
+
+  // Set the AngleSurfaceManager to nullptr to test software fallback path.
+  modifier.SetSurfaceManager(nullptr);
+
+  EXPECT_FALSE(engine->Run());
+}
+
 TEST_F(FlutterWindowsEngineTest, SendPlatformMessageWithoutResponse) {
   FlutterWindowsEngineBuilder builder{GetContext()};
   std::unique_ptr<FlutterWindowsEngine> engine = builder.Build();

shell/platform/windows/testing/flutter_windows_engine_builder.cc

@@ -62,6 +62,10 @@ void FlutterWindowsEngineBuilder::AddDartEntrypointArgument(std::string arg) {
   dart_entrypoint_arguments_.emplace_back(std::move(arg));
 }
 
+void FlutterWindowsEngineBuilder::SetSwitches(std::vector<std::string> switches) {
+  switches_ = std::move(switches);
+}
+
 void FlutterWindowsEngineBuilder::SetCreateKeyboardHandlerCallbacks(
     KeyboardKeyEmbedderHandler::GetKeyStateHandler get_key_state,
     KeyboardKeyEmbedderHandler::MapVirtualKeyToScanCode map_vk_to_scan) {
@@ -86,6 +90,7 @@ std::unique_ptr<FlutterWindowsEngine> FlutterWindowsEngineBuilder::Build() {
   }
 
   FlutterProjectBundle project(properties_);
+  project.SetSwitches(switches_);
 
   return std::make_unique<TestFlutterWindowsEngine>(project, get_key_state_,
                                                     map_vk_to_scan_);

shell/platform/windows/testing/flutter_windows_engine_builder.h

@@ -29,13 +29,16 @@ class FlutterWindowsEngineBuilder {
       KeyboardKeyEmbedderHandler::GetKeyStateHandler get_key_state,
       KeyboardKeyEmbedderHandler::MapVirtualKeyToScanCode map_vk_to_scan);
 
+  void SetSwitches(std::vector<std::string> switches);
+
   std::unique_ptr<FlutterWindowsEngine> Build();
 
  private:
   WindowsTestContext& context_;
   FlutterDesktopEngineProperties properties_ = {};
   std::string dart_entrypoint_;
   std::vector<std::string> dart_entrypoint_arguments_;
+  std::vector<std::string> switches_;
   KeyboardKeyEmbedderHandler::GetKeyStateHandler get_key_state_;
   KeyboardKeyEmbedderHandler::MapVirtualKeyToScanCode map_vk_to_scan_;