diff --git a/packages/react-client/src/ReactFlightReplyClient.js b/packages/react-client/src/ReactFlightReplyClient.js
index 57989237481ed..dc20eb55d2c1b 100644
--- a/packages/react-client/src/ReactFlightReplyClient.js
+++ b/packages/react-client/src/ReactFlightReplyClient.js
@@ -29,6 +29,9 @@ import {
 } from 'shared/ReactSerializationErrors';
 
 import isArray from 'shared/isArray';
+import getPrototypeOf from 'shared/getPrototypeOf';
+
+const ObjectPrototype = Object.prototype;
 
 import {usedWithSSR} from './ReactFlightClientConfig';
 
@@ -227,6 +230,10 @@ export function processReply(
         );
         return serializePromiseID(promiseId);
       }
+      if (isArray(value)) {
+        // $FlowFixMe[incompatible-return]
+        return value;
+      }
       // TODO: Should we the Object.prototype.toString.call() to test for cross-realm objects?
       if (value instanceof FormData) {
         if (formData === null) {
@@ -263,54 +270,60 @@ export function processReply(
         formData.append(formFieldPrefix + setId, partJSON);
         return serializeSetID(setId);
       }
-      if (!isArray(value)) {
-        const iteratorFn = getIteratorFn(value);
-        if (iteratorFn) {
-          return Array.from((value: any));
-        }
+      const iteratorFn = getIteratorFn(value);
+      if (iteratorFn) {
+        return Array.from((value: any));
       }
 
+      // Verify that this is a simple plain object.
+      const proto = getPrototypeOf(value);
+      if (
+        proto !== ObjectPrototype &&
+        (proto === null || getPrototypeOf(proto) !== null)
+      ) {
+        throw new Error(
+          'Only plain objects, and a few built-ins, can be passed to Server Actions. ' +
+            'Classes or null prototypes are not supported.',
+        );
+      }
       if (__DEV__) {
-        if (value !== null && !isArray(value)) {
-          // Verify that this is a simple plain object.
-          if ((value: any).$$typeof === REACT_ELEMENT_TYPE) {
-            console.error(
-              'React Element cannot be passed to Server Functions from the Client.%s',
-              describeObjectForErrorMessage(parent, key),
-            );
-          } else if ((value: any).$$typeof === REACT_LAZY_TYPE) {
-            console.error(
-              'React Lazy cannot be passed to Server Functions from the Client.%s',
-              describeObjectForErrorMessage(parent, key),
-            );
-          } else if ((value: any).$$typeof === REACT_PROVIDER_TYPE) {
-            console.error(
-              'React Context Providers cannot be passed to Server Functions from the Client.%s',
-              describeObjectForErrorMessage(parent, key),
-            );
-          } else if (objectName(value) !== 'Object') {
-            console.error(
-              'Only plain objects can be passed to Client Components from Server Components. ' +
-                '%s objects are not supported.%s',
-              objectName(value),
-              describeObjectForErrorMessage(parent, key),
-            );
-          } else if (!isSimpleObject(value)) {
+        if ((value: any).$$typeof === REACT_ELEMENT_TYPE) {
+          console.error(
+            'React Element cannot be passed to Server Functions from the Client.%s',
+            describeObjectForErrorMessage(parent, key),
+          );
+        } else if ((value: any).$$typeof === REACT_LAZY_TYPE) {
+          console.error(
+            'React Lazy cannot be passed to Server Functions from the Client.%s',
+            describeObjectForErrorMessage(parent, key),
+          );
+        } else if ((value: any).$$typeof === REACT_PROVIDER_TYPE) {
+          console.error(
+            'React Context Providers cannot be passed to Server Functions from the Client.%s',
+            describeObjectForErrorMessage(parent, key),
+          );
+        } else if (objectName(value) !== 'Object') {
+          console.error(
+            'Only plain objects can be passed to Client Components from Server Components. ' +
+              '%s objects are not supported.%s',
+            objectName(value),
+            describeObjectForErrorMessage(parent, key),
+          );
+        } else if (!isSimpleObject(value)) {
+          console.error(
+            'Only plain objects can be passed to Client Components from Server Components. ' +
+              'Classes or other objects with methods are not supported.%s',
+            describeObjectForErrorMessage(parent, key),
+          );
+        } else if (Object.getOwnPropertySymbols) {
+          const symbols = Object.getOwnPropertySymbols(value);
+          if (symbols.length > 0) {
             console.error(
               'Only plain objects can be passed to Client Components from Server Components. ' +
-                'Classes or other objects with methods are not supported.%s',
+                'Objects with symbol properties like %s are not supported.%s',
+              symbols[0].description,
               describeObjectForErrorMessage(parent, key),
             );
-          } else if (Object.getOwnPropertySymbols) {
-            const symbols = Object.getOwnPropertySymbols(value);
-            if (symbols.length > 0) {
-              console.error(
-                'Only plain objects can be passed to Client Components from Server Components. ' +
-                  'Objects with symbol properties like %s are not supported.%s',
-                symbols[0].description,
-                describeObjectForErrorMessage(parent, key),
-              );
-            }
           }
         }
       }
diff --git a/packages/react-client/src/__tests__/ReactFlight-test.js b/packages/react-client/src/__tests__/ReactFlight-test.js
index c0f3d2bbb0b04..c68630e5b23e5 100644
--- a/packages/react-client/src/__tests__/ReactFlight-test.js
+++ b/packages/react-client/src/__tests__/ReactFlight-test.js
@@ -988,19 +988,21 @@ describe('ReactFlight', () => {
     ReactNoopFlightClient.read(transport);
   });
 
-  it('should warn in DEV if a class instance is passed to a host component', () => {
+  it('should error if a class instance is passed to a host component', () => {
     class Foo {
       method() {}
     }
-    expect(() => {
-      const transport = ReactNoopFlightServer.render(
-        <input value={new Foo()} />,
-      );
-      ReactNoopFlightClient.read(transport);
-    }).toErrorDev(
-      'Only plain objects can be passed to Client Components from Server Components. ',
-      {withoutStack: true},
-    );
+    const errors = [];
+    ReactNoopFlightServer.render(<input value={new Foo()} />, {
+      onError(x) {
+        errors.push(x.message);
+      },
+    });
+
+    expect(errors).toEqual([
+      'Only plain objects, and a few built-ins, can be passed to Client Components ' +
+        'from Server Components. Classes or null prototypes are not supported.',
+    ]);
   });
 
   it('should warn in DEV if a a client reference is passed to useContext()', () => {
diff --git a/packages/react-server/src/ReactFlightServer.js b/packages/react-server/src/ReactFlightServer.js
index e8d120b952f1e..6c08dd9948838 100644
--- a/packages/react-server/src/ReactFlightServer.js
+++ b/packages/react-server/src/ReactFlightServer.js
@@ -111,10 +111,13 @@ import {getOrCreateServerContext} from 'shared/ReactServerContextRegistry';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import ReactServerSharedInternals from './ReactServerSharedInternals';
 import isArray from 'shared/isArray';
+import getPrototypeOf from 'shared/getPrototypeOf';
 import binaryToComparableString from 'shared/binaryToComparableString';
 
 import {SuspenseException, getSuspendedThenable} from './ReactFlightThenable';
 
+const ObjectPrototype = Object.prototype;
+
 type JSONValue =
   | string
   | boolean
@@ -1046,6 +1049,11 @@ function resolveModelToJSON(
       return (undefined: any);
     }
 
+    if (isArray(value)) {
+      // $FlowFixMe[incompatible-return]
+      return value;
+    }
+
     if (value instanceof Map) {
       return serializeMap(request, value);
     }
@@ -1107,39 +1115,45 @@ function resolveModelToJSON(
       }
     }
 
-    if (!isArray(value)) {
-      const iteratorFn = getIteratorFn(value);
-      if (iteratorFn) {
-        return Array.from((value: any));
-      }
+    const iteratorFn = getIteratorFn(value);
+    if (iteratorFn) {
+      return Array.from((value: any));
     }
 
+    // Verify that this is a simple plain object.
+    const proto = getPrototypeOf(value);
+    if (
+      proto !== ObjectPrototype &&
+      (proto === null || getPrototypeOf(proto) !== null)
+    ) {
+      throw new Error(
+        'Only plain objects, and a few built-ins, can be passed to Client Components ' +
+          'from Server Components. Classes or null prototypes are not supported.',
+      );
+    }
     if (__DEV__) {
-      if (value !== null && !isArray(value)) {
-        // Verify that this is a simple plain object.
-        if (objectName(value) !== 'Object') {
-          console.error(
-            'Only plain objects can be passed to Client Components from Server Components. ' +
-              '%s objects are not supported.%s',
-            objectName(value),
-            describeObjectForErrorMessage(parent, key),
-          );
-        } else if (!isSimpleObject(value)) {
+      if (objectName(value) !== 'Object') {
+        console.error(
+          'Only plain objects can be passed to Client Components from Server Components. ' +
+            '%s objects are not supported.%s',
+          objectName(value),
+          describeObjectForErrorMessage(parent, key),
+        );
+      } else if (!isSimpleObject(value)) {
+        console.error(
+          'Only plain objects can be passed to Client Components from Server Components. ' +
+            'Classes or other objects with methods are not supported.%s',
+          describeObjectForErrorMessage(parent, key),
+        );
+      } else if (Object.getOwnPropertySymbols) {
+        const symbols = Object.getOwnPropertySymbols(value);
+        if (symbols.length > 0) {
           console.error(
             'Only plain objects can be passed to Client Components from Server Components. ' +
-              'Classes or other objects with methods are not supported.%s',
+              'Objects with symbol properties like %s are not supported.%s',
+            symbols[0].description,
             describeObjectForErrorMessage(parent, key),
           );
-        } else if (Object.getOwnPropertySymbols) {
-          const symbols = Object.getOwnPropertySymbols(value);
-          if (symbols.length > 0) {
-            console.error(
-              'Only plain objects can be passed to Client Components from Server Components. ' +
-                'Objects with symbol properties like %s are not supported.%s',
-              symbols[0].description,
-              describeObjectForErrorMessage(parent, key),
-            );
-          }
         }
       }
     }
diff --git a/packages/react/src/ReactTaint.js b/packages/react/src/ReactTaint.js
index d9e532737be6e..399acb8f01431 100644
--- a/packages/react/src/ReactTaint.js
+++ b/packages/react/src/ReactTaint.js
@@ -9,6 +9,8 @@
 
 import {enableTaint, enableBinaryFlight} from 'shared/ReactFeatureFlags';
 
+import getPrototypeOf from 'shared/getPrototypeOf';
+
 import binaryToComparableString from 'shared/binaryToComparableString';
 
 import ReactServerSharedInternals from './ReactServerSharedInternals';
@@ -22,9 +24,7 @@ const {
 interface Reference {}
 
 // This is the shared constructor of all typed arrays.
-const TypedArrayConstructor = Object.getPrototypeOf(
-  Uint32Array.prototype,
-).constructor;
+const TypedArrayConstructor = getPrototypeOf(Uint32Array.prototype).constructor;
 
 const defaultMessage =
   'A tainted value was attempted to be serialized to a Client Component or Action closure. ' +
diff --git a/packages/shared/ReactSerializationErrors.js b/packages/shared/ReactSerializationErrors.js
index a4875007791f5..e0def3e1c657d 100644
--- a/packages/shared/ReactSerializationErrors.js
+++ b/packages/shared/ReactSerializationErrors.js
@@ -19,6 +19,7 @@ import {
 import type {LazyComponent} from 'react/src/ReactLazy';
 
 import isArray from 'shared/isArray';
+import getPrototypeOf from 'shared/getPrototypeOf';
 
 // Used for DEV messages to keep track of which parent rendered some props,
 // in case they error.
@@ -35,7 +36,7 @@ function isObjectPrototype(object: any): boolean {
   }
   // It might be an object from a different Realm which is
   // still just a plain simple object.
-  if (Object.getPrototypeOf(object)) {
+  if (getPrototypeOf(object)) {
     return false;
   }
   const names = Object.getOwnPropertyNames(object);
@@ -48,7 +49,7 @@ function isObjectPrototype(object: any): boolean {
 }
 
 export function isSimpleObject(object: any): boolean {
-  if (!isObjectPrototype(Object.getPrototypeOf(object))) {
+  if (!isObjectPrototype(getPrototypeOf(object))) {
     return false;
   }
   const names = Object.getOwnPropertyNames(object);
diff --git a/packages/shared/getPrototypeOf.js b/packages/shared/getPrototypeOf.js
new file mode 100644
index 0000000000000..2137bdc1c3947
--- /dev/null
+++ b/packages/shared/getPrototypeOf.js
@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+const getPrototypeOf = Object.getPrototypeOf;
+
+export default getPrototypeOf;
diff --git a/scripts/error-codes/codes.json b/scripts/error-codes/codes.json
index 851c058cf1b2d..b01d1150b2287 100644
--- a/scripts/error-codes/codes.json
+++ b/scripts/error-codes/codes.json
@@ -482,5 +482,7 @@
   "494": "taintUniqueValue cannot taint objects or functions. Try taintObjectReference instead.",
   "495": "Cannot taint a %s because the value is too general and not unique enough to block globally.",
   "496": "Only objects or functions can be passed to taintObjectReference. Try taintUniqueValue instead.",
-  "497": "Only objects or functions can be passed to taintObjectReference."
+  "497": "Only objects or functions can be passed to taintObjectReference.",
+  "498": "Only plain objects, and a few built-ins, can be passed to Client Components from Server Components. Classes or null prototypes are not supported.",
+  "499": "Only plain objects, and a few built-ins, can be passed to Server Actions. Classes or null prototypes are not supported."
 }
\ No newline at end of file