diff --git a/third_party/packages/mustache_template/CHANGELOG.md b/third_party/packages/mustache_template/CHANGELOG.md
index 83bf7da3b5b3..67f53c1a8fc9 100644
--- a/third_party/packages/mustache_template/CHANGELOG.md
+++ b/third_party/packages/mustache_template/CHANGELOG.md
@@ -1,6 +1,8 @@
-## NEXT
+## 2.0.3
 
 * Updates minimum supported SDK version to Flutter 3.35/Dart 3.9.
+* Fixes error handling in LambdaContext by adding missing throw statements.
+* Uses StateError instead of Exception for unreachable code in parser.
 
 ## 2.0.2
 
diff --git a/third_party/packages/mustache_template/lib/src/lambda_context.dart b/third_party/packages/mustache_template/lib/src/lambda_context.dart
index ca4082f0ea33..3cd72c3ee092 100644
--- a/third_party/packages/mustache_template/lib/src/lambda_context.dart
+++ b/third_party/packages/mustache_template/lib/src/lambda_context.dart
@@ -38,9 +38,7 @@ class LambdaContext implements m.LambdaContext {
   String renderString({Object? value}) {
     _checkClosed();
     if (_node is! SectionNode) {
-      // TODO(stuartmorgan): Fix the lack of `throw` here, which looks like a
-      //  bug in the original code.
-      _error(
+      throw _error(
         'LambdaContext.renderString() can only be called on section tags.',
       );
     }
@@ -62,9 +60,9 @@ class LambdaContext implements m.LambdaContext {
   void render({Object? value}) {
     _checkClosed();
     if (_node is! SectionNode) {
-      // TODO(stuartmorgan): Fix the lack of `throw` here, which looks like a
-      //  bug in the original code.
-      _error('LambdaContext.render() can only be called on section tags.');
+      throw _error(
+        'LambdaContext.render() can only be called on section tags.',
+      );
     }
     _renderSubtree(_renderer.sink, value);
   }
diff --git a/third_party/packages/mustache_template/lib/src/parser.dart b/third_party/packages/mustache_template/lib/src/parser.dart
index a6dc3b1e8b29..4253ec312aa4 100644
--- a/third_party/packages/mustache_template/lib/src/parser.dart
+++ b/third_party/packages/mustache_template/lib/src/parser.dart
@@ -98,8 +98,7 @@ class Parser {
           _parseLine();
 
         default:
-          // TODO(stuartmorgan): Convert to StateError.
-          throw Exception('Unreachable code.');
+          throw StateError('Unreachable code.');
       }
     }
 
@@ -212,8 +211,7 @@ class Parser {
         break;
 
       default:
-        // TODO(stuartmorgan): Convert to StateError.
-        throw Exception('Unreachable code.');
+        throw StateError('Unreachable code.');
     }
   }
 
@@ -412,8 +410,7 @@ class Parser {
         node = null;
 
       default:
-        // TODO(stuartmorgan): Convert to StateError.
-        throw Exception('Unreachable code');
+        throw StateError('Unreachable code.');
     }
     return node;
   }
diff --git a/third_party/packages/mustache_template/pubspec.yaml b/third_party/packages/mustache_template/pubspec.yaml
index 30e2128afb1e..264e0ee0c4d4 100644
--- a/third_party/packages/mustache_template/pubspec.yaml
+++ b/third_party/packages/mustache_template/pubspec.yaml
@@ -2,7 +2,7 @@ name: mustache_template
 description: A templating library that implements the Mustache template specification
 repository: https://github.com/flutter/packages/tree/main/third_party/packages/mustache_template
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+mustache_template%22
-version: 2.0.2
+version: 2.0.3
 
 environment:
   sdk: ^3.9.0
diff --git a/third_party/packages/mustache_template/test/mustache_test.dart b/third_party/packages/mustache_template/test/mustache_test.dart
index 5fffe6502884..a8149220ba76 100644
--- a/third_party/packages/mustache_template/test/mustache_test.dart
+++ b/third_party/packages/mustache_template/test/mustache_test.dart
@@ -883,6 +883,29 @@ void main() {
       const output = '<oi!>';
       expect(parse(template).renderString(values), equals(output));
     });
+
+    test('LambdaContext renderString on non-section throws', () {
+      final t = Template('{{ foo }}');
+      expect(
+        () => t.renderString(<String, Object>{
+          'foo': (LambdaContext lc) => lc.renderString(),
+        }),
+        throwsA(isA<TemplateException>()),
+      );
+    });
+
+    test('LambdaContext render on non-section throws', () {
+      final t = Template('{{ foo }}');
+      expect(
+        () => t.renderString(<String, Object>{
+          'foo': (LambdaContext lc) {
+            lc.render();
+            return '';
+          },
+        }),
+        throwsA(isA<TemplateException>()),
+      );
+    });
   });
 }