diff --git a/pkg/front_end/lib/src/fasta/source/diet_listener.dart b/pkg/front_end/lib/src/fasta/source/diet_listener.dart
index c3726219c6760..f5617496580d7 100644
--- a/pkg/front_end/lib/src/fasta/source/diet_listener.dart
+++ b/pkg/front_end/lib/src/fasta/source/diet_listener.dart
@@ -97,6 +97,7 @@ class DietListener extends StackListenerImpl {
 
   DeclarationBuilder _currentDeclaration;
   ClassBuilder _currentClass;
+  bool _inRedirectingFactory = false;
 
   bool currentClassIsParserRecovery = false;
 
@@ -590,7 +591,7 @@ class DietListener extends StackListenerImpl {
     if (name is ParserRecovery || currentClassIsParserRecovery) return;
 
     FunctionBuilder builder = lookupConstructor(beginToken, name);
-    if (bodyToken == null || optional("=", bodyToken.endGroup.next)) {
+    if (_inRedirectingFactory) {
       buildRedirectingFactoryMethod(
           bodyToken, builder, MemberKind.Factory, metadata);
     } else {
@@ -625,6 +626,7 @@ class DietListener extends StackListenerImpl {
   void endRedirectingFactoryBody(Token beginToken, Token endToken) {
     debugEvent("RedirectingFactoryBody");
     discard(1); // ConstructorReference.
+    _inRedirectingFactory = true;
   }
 
   @override
@@ -793,6 +795,7 @@ class DietListener extends StackListenerImpl {
   void endMember() {
     debugEvent("Member");
     checkEmpty(-1);
+    _inRedirectingFactory = false;
   }
 
   @override
@@ -933,6 +936,11 @@ class DietListener extends StackListenerImpl {
       token = parser.parseInitializersOpt(token);
       token = parser.parseAsyncModifierOpt(token);
       AsyncMarker asyncModifier = getAsyncMarker(listener) ?? AsyncMarker.Sync;
+      if (kind == MemberKind.Factory && asyncModifier != AsyncMarker.Sync) {
+        // Factories has to be sync. The parser issued an error.
+        // Recover to sync.
+        asyncModifier = AsyncMarker.Sync;
+      }
       bool isExpression = false;
       bool allowAbstract = asyncModifier == AsyncMarker.Sync;
       parser.parseFunctionBody(token, isExpression, allowAbstract);
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml
index 10b94fd0e6ab9..1b6622896ba9f 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml
@@ -9,13 +9,31 @@ worlds:
   - entry: main.dart
     sources:
       main.dart: |
+        import "lib.dart";
+        void main() {
+          var c = new C.e4();
+        }
+      lib.dart: |
         class C {
           C();
           factory C.e4() async = C;
         }
-
+    expectedLibraryCount: 2
+    errors: true
+  - entry: main.dart
+    invalidate:
+      - main.dart
+    sources:
+      main.dart: |
+        import "lib.dart";
         void main() {
           var c = new C.e4();
+          print(c);
+        }
+      lib.dart: |
+        class C {
+          C();
+          factory C.e4() async = C;
         }
-    expectedLibraryCount: 1
+    expectedLibraryCount: 2
     errors: true
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.1.expect
index 10227fce20574..bd5a25a79e7da 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.1.expect
@@ -1,63 +1,27 @@
 main = <No Member>;
-library from "org-dartlang-test:///main.dart" as main {
+library from "org-dartlang-test:///lib.dart" as lib {
 //
 // Problems in library:
 //
-// org-dartlang-test:///main.dart:3:11: Error: Functions marked 'async' must have a return type assignable to 'Future'.
-//   factory C.e4() async = C;
-//           ^^
-//
-// org-dartlang-test:///main.dart:3:18: Error: Factory bodies can't use 'async', 'async*', or 'sync*'.
+// org-dartlang-test:///lib.dart:3:18: Error: Factory bodies can't use 'async', 'async*', or 'sync*'.
 //   factory C.e4() async = C;
 //                  ^^^^^
-//
-// org-dartlang-test:///main.dart:3:24: Error: Expected a function body or '=>'.
-// Try adding {}.
-//   factory C.e4() async = C;
-//                        ^
-//
-// org-dartlang-test:///main.dart:3:26: Error: A value of type 'Type' can't be assigned to a variable of type 'FutureOr<C>'.
-//  - 'Type' is from 'dart:core'.
-//  - 'FutureOr' is from 'dart:async'.
-//  - 'C' is from 'org-dartlang-test:///main.dart'.
-//   factory C.e4() async = C;
-//                          ^
 //
 
   class C extends dart.core::Object {
-    static field dynamic _redirecting# = <dynamic>[main::C::e4];
-    constructor •() → main::C*
+    static field dynamic _redirecting# = <dynamic>[lib::C::e4];
+    constructor •() → lib::C*
       : super dart.core::Object::•()
       ;
-    static factory e4() → main::C* /* originally async */ {
-      final dart.async::_AsyncAwaitCompleter<dynamic>* :async_completer = new dart.async::_AsyncAwaitCompleter::•<dynamic>();
-      dart.async::FutureOr<dynamic>* :return_value;
-      dynamic :async_stack_trace;
-      dynamic :async_op_then;
-      dynamic :async_op_error;
-      dart.core::int* :await_jump_var = 0;
-      dynamic :await_ctx_var;
-      function :async_op([dynamic :result, dynamic :exception, dynamic :stack_trace]) → dynamic yielding 
-        try {
-          #L1:
-          {
-            :return_value = let final<BottomType> #t1 = invalid-expression "org-dartlang-test:///main.dart:3:26: Error: A value of type 'Type' can't be assigned to a variable of type 'FutureOr<C>'.\n - 'Type' is from 'dart:core'.\n - 'FutureOr' is from 'dart:async'.\n - 'C' is from 'org-dartlang-test:///main.dart'.\n  factory C.e4() async = C;\n                         ^" in main::C* as{TypeError} dart.async::FutureOr<main::C*>*;
-            break #L1;
-          }
-          dart.async::_completeOnAsyncReturn(:async_completer, :return_value);
-          return;
-        }
-        on dynamic catch(dynamic :exception, dynamic :stack_trace) {
-          :async_completer.{dart.async::Completer::completeError}(:exception, :stack_trace);
-        }
-      :async_stack_trace = dart.async::_asyncStackTraceHelper(:async_op);
-      :async_op_then = dart.async::_asyncThenWrapperHelper(:async_op);
-      :async_op_error = dart.async::_asyncErrorWrapperHelper(:async_op);
-      :async_completer.start(:async_op);
-      return :async_completer.{dart.async::Completer::future};
-    }
+    static factory e4() → lib::C*
+      let dynamic #redirecting_factory = lib::C::• in invalid-expression;
   }
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib.dart";
+
   static method main() → void {
-    main::C* c = main::C::e4();
+    lib::C* c = new lib::C::•();
   }
 }
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.2.expect
new file mode 100644
index 0000000000000..8ef39f628966e
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/crash_test_1.yaml.world.2.expect
@@ -0,0 +1,28 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib.dart" as lib {
+//
+// Problems in library:
+//
+// org-dartlang-test:///lib.dart:3:18: Error: Factory bodies can't use 'async', 'async*', or 'sync*'.
+//   factory C.e4() async = C;
+//                  ^^^^^
+//
+
+  class C extends dart.core::Object {
+    static field dynamic _redirecting# = <dynamic>[lib::C::e4];
+    constructor •() → lib::C*
+      : super dart.core::Object::•()
+      ;
+    static factory e4() → lib::C*
+      let dynamic #redirecting_factory = lib::C::• in invalid-expression;
+  }
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib.dart";
+
+  static method main() → void {
+    lib::C* c = new lib::C::•();
+    dart.core::print(c);
+  }
+}