diff --git a/frb_example/pure_dart/test/api/exception_test.dart b/frb_example/pure_dart/test/api/exception_test.dart
index fceea2952d..c953b51a91 100644
--- a/frb_example/pure_dart/test/api/exception_test.dart
+++ b/frb_example/pure_dart/test/api/exception_test.dart
@@ -210,7 +210,8 @@ Future<void> main({bool skipRustLibInit = false}) async {
   });
 
   group('has backtraces', skip: kIsWeb, () {
-    final matcher = anyOf(contains('.rs'), contains('::'));
+    final matcher =
+        anyOf(contains('.rs'), contains('::'), contains('<unknown>'));
 
     test('when error (Result::Err)', () async {
       await expectLater(
diff --git a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_sse_test.dart b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_sse_test.dart
index 9536572ec9..7e5419b1f4 100644
--- a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_sse_test.dart
+++ b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_sse_test.dart
@@ -227,7 +227,8 @@ Future<void> main({bool skipRustLibInit = false}) async {
   });
 
   group('has backtraces', skip: kIsWeb, () {
-    final matcher = anyOf(contains('.rs'), contains('::'));
+    final matcher =
+        anyOf(contains('.rs'), contains('::'), contains('<unknown>'));
 
     test('when error (Result::Err)', () async {
       await expectLater(
diff --git a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_test.dart b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_test.dart
index b3204fd3da..d88d17e8be 100644
--- a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_test.dart
+++ b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_rust_async_test.dart
@@ -221,7 +221,8 @@ Future<void> main({bool skipRustLibInit = false}) async {
   });
 
   group('has backtraces', skip: kIsWeb, () {
-    final matcher = anyOf(contains('.rs'), contains('::'));
+    final matcher =
+        anyOf(contains('.rs'), contains('::'), contains('<unknown>'));
 
     test('when error (Result::Err)', () async {
       await expectLater(
diff --git a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sse_test.dart b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sse_test.dart
index 9455bea864..ed5596323c 100644
--- a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sse_test.dart
+++ b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sse_test.dart
@@ -209,7 +209,8 @@ Future<void> main({bool skipRustLibInit = false}) async {
   });
 
   group('has backtraces', skip: kIsWeb, () {
-    final matcher = anyOf(contains('.rs'), contains('::'));
+    final matcher =
+        anyOf(contains('.rs'), contains('::'), contains('<unknown>'));
 
     test('when error (Result::Err)', () async {
       await expectLater(
diff --git a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_sse_test.dart b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_sse_test.dart
index fbae6df8b4..dffbd4c228 100644
--- a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_sse_test.dart
+++ b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_sse_test.dart
@@ -216,7 +216,8 @@ Future<void> main({bool skipRustLibInit = false}) async {
   });
 
   group('has backtraces', skip: kIsWeb, () {
-    final matcher = anyOf(contains('.rs'), contains('::'));
+    final matcher =
+        anyOf(contains('.rs'), contains('::'), contains('<unknown>'));
 
     test('when error (Result::Err)', () async {
       await expectLater(
diff --git a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_test.dart b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_test.dart
index baa1df7f44..f6e0795655 100644
--- a/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_test.dart
+++ b/frb_example/pure_dart/test/api/pseudo_manual/exception_twin_sync_test.dart
@@ -210,7 +210,8 @@ Future<void> main({bool skipRustLibInit = false}) async {
   });
 
   group('has backtraces', skip: kIsWeb, () {
-    final matcher = anyOf(contains('.rs'), contains('::'));
+    final matcher =
+        anyOf(contains('.rs'), contains('::'), contains('<unknown>'));
 
     test('when error (Result::Err)', () async {
       await expectLater(