diff --git a/packages/react-native/Libraries/Blob/FileReader.js b/packages/react-native/Libraries/Blob/FileReader.js
index f8154bd2373..d68989018f1 100644
--- a/packages/react-native/Libraries/Blob/FileReader.js
+++ b/packages/react-native/Libraries/Blob/FileReader.js
@@ -34,7 +34,7 @@ const EMPTY = 0;
 const LOADING = 1;
 const DONE = 2;
 
-class FileReader extends (EventTarget(...READER_EVENTS): any) {
+class FileReader extends (EventTarget(...READER_EVENTS): typeof EventTarget) {
   static EMPTY: number = EMPTY;
   static LOADING: number = LOADING;
   static DONE: number = DONE;
diff --git a/packages/react-native/Libraries/Network/XMLHttpRequest.js b/packages/react-native/Libraries/Network/XMLHttpRequest.js
index 2664f8ab890..458f0780a0f 100644
--- a/packages/react-native/Libraries/Network/XMLHttpRequest.js
+++ b/packages/react-native/Libraries/Network/XMLHttpRequest.js
@@ -78,7 +78,9 @@ const REQUEST_EVENTS = [
 
 const XHR_EVENTS = REQUEST_EVENTS.concat('readystatechange');
 
-class XMLHttpRequestEventTarget extends (EventTarget(...REQUEST_EVENTS): any) {
+class XMLHttpRequestEventTarget extends (EventTarget(
+  ...REQUEST_EVENTS,
+): typeof EventTarget) {
   onload: ?Function;
   onloadstart: ?Function;
   onprogress: ?Function;
@@ -91,7 +93,7 @@ class XMLHttpRequestEventTarget extends (EventTarget(...REQUEST_EVENTS): any) {
 /**
  * Shared base for platform-specific XMLHttpRequest implementations.
  */
-class XMLHttpRequest extends (EventTarget(...XHR_EVENTS): any) {
+class XMLHttpRequest extends (EventTarget(...XHR_EVENTS): typeof EventTarget) {
   static UNSENT: number = UNSENT;
   static OPENED: number = OPENED;
   static HEADERS_RECEIVED: number = HEADERS_RECEIVED;
diff --git a/packages/react-native/Libraries/WebSocket/WebSocket.js b/packages/react-native/Libraries/WebSocket/WebSocket.js
index 3fdde2b3639..08d737493c3 100644
--- a/packages/react-native/Libraries/WebSocket/WebSocket.js
+++ b/packages/react-native/Libraries/WebSocket/WebSocket.js
@@ -68,7 +68,7 @@ type WebSocketEventDefinitions = {
  * See https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
  * See https://github.com/websockets/ws
  */
-class WebSocket extends (EventTarget(...WEBSOCKET_EVENTS): any) {
+class WebSocket extends (EventTarget(...WEBSOCKET_EVENTS): typeof EventTarget) {
   static CONNECTING: number = CONNECTING;
   static OPEN: number = OPEN;
   static CLOSING: number = CLOSING;
diff --git a/packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap b/packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap
index 93109e9e4ea..fdcb485b26a 100644
--- a/packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap
+++ b/packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap
@@ -1476,6 +1476,35 @@ declare module.exports: File;
 "
 `;
 
+exports[`public API should not change unintentionally Libraries/Blob/FileReader.js 1`] = `
+"type ReadyState = 0 | 1 | 2;
+type ReaderResult = string | ArrayBuffer;
+declare class FileReader extends EventTarget {
+  static EMPTY: number;
+  static LOADING: number;
+  static DONE: number;
+  EMPTY: number;
+  LOADING: number;
+  DONE: number;
+  _readyState: ReadyState;
+  _error: ?Error;
+  _result: ?ReaderResult;
+  _aborted: boolean;
+  constructor(): void;
+  _reset(): void;
+  _setReadyState(newState: ReadyState): void;
+  readAsArrayBuffer(blob: ?Blob): void;
+  readAsDataURL(blob: ?Blob): void;
+  readAsText(blob: ?Blob, encoding: string): void;
+  abort(): void;
+  get readyState(): ReadyState;
+  get error(): ?Error;
+  get result(): ?ReaderResult;
+}
+declare module.exports: FileReader;
+"
+`;
+
 exports[`public API should not change unintentionally Libraries/Blob/NativeBlobModule.js 1`] = `
 "export * from \\"../../src/private/specs/modules/NativeBlobModule\\";
 declare export default typeof NativeBlobModule;
@@ -6966,6 +6995,130 @@ declare export default typeof RCTNetworking;
 
 exports[`public API should not change unintentionally Libraries/Network/XHRInterceptor.js 1`] = `"UNTYPED MODULE"`;
 
+exports[`public API should not change unintentionally Libraries/Network/XMLHttpRequest.js 1`] = `
+"export type NativeResponseType = \\"base64\\" | \\"blob\\" | \\"text\\";
+export type ResponseType =
+  | \\"\\"
+  | \\"arraybuffer\\"
+  | \\"blob\\"
+  | \\"document\\"
+  | \\"json\\"
+  | \\"text\\";
+export type Response = ?Object | string;
+type XHRInterceptor = interface {
+  requestSent(id: number, url: string, method: string, headers: Object): void,
+  responseReceived(
+    id: number,
+    url: string,
+    status: number,
+    headers: Object
+  ): void,
+  dataReceived(id: number, data: string): void,
+  loadingFinished(id: number, encodedDataLength: number): void,
+  loadingFailed(id: number, error: string): void,
+};
+declare class XMLHttpRequestEventTarget extends EventTarget {
+  onload: ?Function;
+  onloadstart: ?Function;
+  onprogress: ?Function;
+  ontimeout: ?Function;
+  onerror: ?Function;
+  onabort: ?Function;
+  onloadend: ?Function;
+}
+declare class XMLHttpRequest extends EventTarget {
+  static UNSENT: number;
+  static OPENED: number;
+  static HEADERS_RECEIVED: number;
+  static LOADING: number;
+  static DONE: number;
+  static _interceptor: ?XHRInterceptor;
+  UNSENT: number;
+  OPENED: number;
+  HEADERS_RECEIVED: number;
+  LOADING: number;
+  DONE: number;
+  onload: ?Function;
+  onloadstart: ?Function;
+  onprogress: ?Function;
+  ontimeout: ?Function;
+  onerror: ?Function;
+  onabort: ?Function;
+  onloadend: ?Function;
+  onreadystatechange: ?Function;
+  readyState: number;
+  responseHeaders: ?Object;
+  status: number;
+  timeout: number;
+  responseURL: ?string;
+  withCredentials: boolean;
+  upload: XMLHttpRequestEventTarget;
+  _requestId: ?number;
+  _subscriptions: Array<EventSubscription>;
+  _aborted: boolean;
+  _cachedResponse: Response;
+  _hasError: boolean;
+  _headers: Object;
+  _lowerCaseResponseHeaders: Object;
+  _method: ?string;
+  _perfKey: ?string;
+  _responseType: ResponseType;
+  _response: string;
+  _sent: boolean;
+  _url: ?string;
+  _timedOut: boolean;
+  _trackingName: string;
+  _incrementalEvents: boolean;
+  _performanceLogger: IPerformanceLogger;
+  static setInterceptor(interceptor: ?XHRInterceptor): void;
+  constructor(): void;
+  _reset(): void;
+  get responseType(): ResponseType;
+  set responseType(responseType: ResponseType): void;
+  get responseText(): string;
+  get response(): Response;
+  __didCreateRequest(requestId: number): void;
+  __didUploadProgress(requestId: number, progress: number, total: number): void;
+  __didReceiveResponse(
+    requestId: number,
+    status: number,
+    responseHeaders: ?Object,
+    responseURL: ?string
+  ): void;
+  __didReceiveData(requestId: number, response: string): void;
+  __didReceiveIncrementalData(
+    requestId: number,
+    responseText: string,
+    progress: number,
+    total: number
+  ): void;
+  __didReceiveDataProgress(
+    requestId: number,
+    loaded: number,
+    total: number
+  ): void;
+  __didCompleteResponse(
+    requestId: number,
+    error: string,
+    timeOutError: boolean
+  ): void;
+  _clearSubscriptions(): void;
+  getAllResponseHeaders(): ?string;
+  getResponseHeader(header: string): ?string;
+  setRequestHeader(header: string, value: any): void;
+  setTrackingName(trackingName: string): XMLHttpRequest;
+  setPerformanceLogger(performanceLogger: IPerformanceLogger): XMLHttpRequest;
+  open(method: string, url: string, async: ?boolean): void;
+  send(data: any): void;
+  abort(): void;
+  setResponseHeaders(responseHeaders: ?Object): void;
+  setReadyState(newState: number): void;
+  addEventListener(type: string, listener: EventListener): void;
+}
+declare module.exports: XMLHttpRequest;
+"
+`;
+
 exports[`public API should not change unintentionally Libraries/Network/convertRequestBody.js 1`] = `
 "export type RequestBody =
   | string
@@ -9994,6 +10147,69 @@ declare export default typeof NativeWebSocketModule;
 "
 `;
 
+exports[`public API should not change unintentionally Libraries/WebSocket/WebSocket.js 1`] = `
+"type ArrayBufferView =
+  | Int8Array
+  | Uint8Array
+  | Uint8ClampedArray
+  | Int16Array
+  | Uint16Array
+  | Int32Array
+  | Uint32Array
+  | Float32Array
+  | Float64Array
+  | DataView;
+type BinaryType = \\"blob\\" | \\"arraybuffer\\";
+type WebSocketEventDefinitions = {
+  websocketOpen: [{ id: number, protocol: string }],
+  websocketClosed: [{ id: number, code: number, reason: string }],
+  websocketMessage: [
+    | { type: \\"binary\\", id: number, data: string }
+    | { type: \\"text\\", id: number, data: string }
+    | { type: \\"blob\\", id: number, data: BlobData },
+  ],
+  websocketFailed: [{ id: number, message: string }],
+};
+declare class WebSocket extends EventTarget {
+  static CONNECTING: number;
+  static OPEN: number;
+  static CLOSING: number;
+  static CLOSED: number;
+  CONNECTING: number;
+  OPEN: number;
+  CLOSING: number;
+  CLOSED: number;
+  _socketId: number;
+  _eventEmitter: NativeEventEmitter<WebSocketEventDefinitions>;
+  _subscriptions: Array<EventSubscription>;
+  _binaryType: ?BinaryType;
+  onclose: ?Function;
+  onerror: ?Function;
+  onmessage: ?Function;
+  onopen: ?Function;
+  bufferedAmount: number;
+  extension: ?string;
+  protocol: ?string;
+  readyState: number;
+  url: ?string;
+  constructor(
+    url: string,
+    protocols: ?string | ?Array<string>,
+    options: ?{ headers?: { origin?: string, ... }, ... }
+  ): void;
+  get binaryType(): ?BinaryType;
+  set binaryType(binaryType: BinaryType): void;
+  close(code?: number, reason?: string): void;
+  send(data: string | ArrayBuffer | ArrayBufferView | Blob): void;
+  ping(): void;
+  _close(code?: number, reason?: string): void;
+  _unregisterEvents(): void;
+  _registerEvents(): void;
+}
+declare module.exports: WebSocket;
+"
+`;
+
 exports[`public API should not change unintentionally Libraries/WebSocket/WebSocketEvent.js 1`] = `"UNTYPED MODULE"`;
 
 exports[`public API should not change unintentionally Libraries/WebSocket/WebSocketInterceptor.js 1`] = `"UNTYPED MODULE"`;
diff --git a/packages/react-native/Libraries/__tests__/public-api-test.js b/packages/react-native/Libraries/__tests__/public-api-test.js
index ba51ace8f83..f70fb39f80c 100644
--- a/packages/react-native/Libraries/__tests__/public-api-test.js
+++ b/packages/react-native/Libraries/__tests__/public-api-test.js
@@ -29,10 +29,6 @@ const IGNORE_PATTERNS = [
 // Exclude list for files that fail to parse under flow-api-translator. Please
 // review your changes before adding new entries.
 const FILES_WITH_KNOWN_ERRORS = new Set([
-  'Libraries/Blob/FileReader.js',
-  'Libraries/Network/XMLHttpRequest.js',
-  'Libraries/WebSocket/WebSocket.js',
-
   // Parse errors introduced in hermes-parser 0.23.0:  Error: Comment location overlaps with node location
   'Libraries/Core/checkNativeVersion.js',
   'Libraries/Core/InitializeCore.js',
@@ -84,13 +80,15 @@ describe('public API', () => {
           success = true;
         } catch (e) {
           if (!FILES_WITH_KNOWN_ERRORS.has(file)) {
-            console.error('Unable to parse file:', file, '\n' + e);
+            throw new Error(
+              'Unable to parse file: ' + file + '\n\n' + e.message,
+            );
           }
         } finally {
           if (success && FILES_WITH_KNOWN_ERRORS.has(file)) {
-            console.error(
-              'Expected parse error, please remove file exclude from FILES_WITH_KNOWN_ERRORS:',
-              file,
+            throw new Error(
+              'Expected parse error, please remove file exclude from FILES_WITH_KNOWN_ERRORS: ' +
+                file,
             );
           }
         }