diff --git a/Libraries/RCTTest/RCTTestRunner.m b/Libraries/RCTTest/RCTTestRunner.m
index 08db1eddaad487..bd790467034896 100644
--- a/Libraries/RCTTest/RCTTestRunner.m
+++ b/Libraries/RCTTest/RCTTestRunner.m
@@ -199,7 +199,9 @@ - (void)runTest:(SEL)test module:(NSString *)moduleName
     if (expectErrorBlock) {
       RCTAssert(expectErrorBlock(errors[0]), @"Expected an error but the first one was missing or did not match.");
     } else {
-      RCTAssert(errors == nil, @"RedBox errors: %@", errors);
+      // [TODO(OSS Candidate ISS#2710739): xcpretty formats the test failure output to show only one line of the assert string followed by a snippet of source code including the assert statement and the lines just before and after.
+      // Convert the `errors` array into a single line string delimited by \n so that CI logs contain meaningful information.
+      RCTAssert(errors == nil, @"RedBox errors: %@", [[errors valueForKey:@"description"] componentsJoinedByString:@"\\n"]); // ]TODO(OSS Candidate ISS#2710739)
       RCTAssert(testModule.status != RCTTestStatusPending, @"Test didn't finish within %0.f seconds", kTestTimeoutSeconds);
       RCTAssert(testModule.status == RCTTestStatusPassed, @"Test failed");
     }
diff --git a/Libraries/WebSocket/WebSocket.js b/Libraries/WebSocket/WebSocket.js
index a954175fc0ce1a..2d6cd5c4c98f6f 100644
--- a/Libraries/WebSocket/WebSocket.js
+++ b/Libraries/WebSocket/WebSocket.js
@@ -224,7 +224,11 @@ class WebSocket extends EventTarget(...WEBSOCKET_EVENTS) {
   }
 
   _close(code?: number, reason?: string): void {
-    if (Platform.OS === 'android' || Platform.OS === 'win32' || Platform.OS == 'windesktop') {
+    if (
+      Platform.OS === 'android' ||
+      Platform.OS === 'win32' ||
+      Platform.OS === 'windesktop'
+    ) {
       // See https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent
       const statusCode = typeof code === 'number' ? code : CLOSE_NORMAL;
       const closeReason = typeof reason === 'string' ? reason : '';
diff --git a/RNTester/js/RNTesterApp.ios.js b/RNTester/js/RNTesterApp.ios.js
index 7d5b1a1b23910a..e5697e7d8b3458 100644
--- a/RNTester/js/RNTesterApp.ios.js
+++ b/RNTester/js/RNTesterApp.ios.js
@@ -58,13 +58,21 @@ const Header = ({onBack, title}: {onBack?: () => mixed, title: string}) => (
 );
 
 class RNTesterApp extends React.Component<Props, RNTesterNavigationState> {
+  _mounted: boolean; // TODO(OSS Candidate ISS#2710739)
+
   UNSAFE_componentWillMount() {
     BackHandler.addEventListener('hardwareBackPress', this._handleBack);
   }
 
   componentDidMount() {
+    this._mounted = true; // TODO(OSS Candidate ISS#2710739)
     Linking.getInitialURL().then(url => {
       AsyncStorage.getItem(APP_STATE_KEY, (err, storedString) => {
+        // [TODO(OSS Candidate ISS#2710739)
+        if (!this._mounted) {
+          return;
+        }
+        // ]TODO(OSS Candidate ISS#2710739)
         const exampleAction = URIActionMap(
           this.props.exampleFromAppetizeParams,
         );
@@ -89,6 +97,12 @@ class RNTesterApp extends React.Component<Props, RNTesterNavigationState> {
     });
   }
 
+  // [TODO(OSS Candidate ISS#2710739)
+  componentWillUnmount() {
+    this._mounted = false;
+  }
+  // ]TODO(OSS Candidate ISS#2710739)
+
   _handleBack = () => {
     this._handleAction(RNTesterActions.Back());
   };
diff --git a/RNTester/js/RNTesterApp.macos.js b/RNTester/js/RNTesterApp.macos.js
index c5af64a394511c..440b7d3281c427 100644
--- a/RNTester/js/RNTesterApp.macos.js
+++ b/RNTester/js/RNTesterApp.macos.js
@@ -60,13 +60,21 @@ const Header = ({onBack, title}: {onBack?: () => mixed, title: string}) => (
 );
 
 class RNTesterApp extends React.Component<Props, RNTesterNavigationState> {
+  _mounted: boolean; // TODO(OSS Candidate ISS#2710739)
+
   UNSAFE_componentWillMount() {
     //  BackHandler.addEventListener('hardwareBackPress', this._handleBack);
   }
 
   componentDidMount() {
+    this._mounted = true; // TODO(OSS Candidate ISS#2710739)
     Linking.getInitialURL().then(url => {
       AsyncStorage.getItem(APP_STATE_KEY, (err, storedString) => {
+        // [TODO(OSS Candidate ISS#2710739)
+        if (!this._mounted) {
+          return;
+        }
+        // ]TODO(OSS Candidate ISS#2710739)
         const exampleAction = URIActionMap(
           this.props.exampleFromAppetizeParams,
         );
@@ -91,6 +99,12 @@ class RNTesterApp extends React.Component<Props, RNTesterNavigationState> {
     });
   }
 
+  // [TODO(OSS Candidate ISS#2710739)
+  componentWillUnmount() {
+    this._mounted = false;
+  }
+  // ]TODO(OSS Candidate ISS#2710739)
+
   _handleBack = () => {
     this._handleAction(RNTesterActions.Back());
   };