diff --git a/fixtures/dom/public/act-dom.html b/fixtures/dom/public/act-dom.html
index 2aa33da465e26..76366998b22b9 100644
--- a/fixtures/dom/public/act-dom.html
+++ b/fixtures/dom/public/act-dom.html
@@ -7,6 +7,7 @@
     this page tests whether act runs properly in a browser.
     <br />
     your console should say "5"
+    <div id='app'/>
     <script src="scheduler-unstable_mock.development.js"></script>
     <script src="react.development.js"></script>
     <script type="text/javascript">
diff --git a/packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js b/packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js
index fd286f1e68c8e..3c6d08110324a 100644
--- a/packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js
+++ b/packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js
@@ -709,9 +709,9 @@ describe('ReactComponentLifeCycle', () => {
       );
     }).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -748,9 +748,9 @@ describe('ReactComponentLifeCycle', () => {
       );
     }).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -815,7 +815,10 @@ describe('ReactComponentLifeCycle', () => {
         {withoutStack: true},
       );
     }).toLowPriorityWarnDev(
-      ['componentWillMount is deprecated', 'componentWillUpdate is deprecated'],
+      [
+        'componentWillMount has been renamed',
+        'componentWillUpdate has been renamed',
+      ],
       {withoutStack: true},
     );
 
@@ -863,7 +866,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillMount is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
       withoutStack: true,
     });
 
@@ -887,7 +890,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillReceiveProps is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillReceiveProps has been renamed'], {
       withoutStack: true,
     });
   });
@@ -921,7 +924,10 @@ describe('ReactComponentLifeCycle', () => {
         {withoutStack: true},
       );
     }).toLowPriorityWarnDev(
-      ['componentWillMount is deprecated', 'componentWillUpdate is deprecated'],
+      [
+        'componentWillMount has been renamed',
+        'componentWillUpdate has been renamed',
+      ],
       {withoutStack: true},
     );
 
@@ -967,7 +973,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillMount is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
       withoutStack: true,
     });
 
@@ -990,7 +996,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillReceiveProps is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillReceiveProps has been renamed'], {
       withoutStack: true,
     });
   });
@@ -1130,9 +1136,9 @@ describe('ReactComponentLifeCycle', () => {
       ReactDOM.render(<MyComponent foo="bar" />, div),
     ).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -1403,17 +1409,9 @@ describe('ReactComponentLifeCycle', () => {
       ReactDOM.render(<MyComponent x={1} />, container),
     ).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated and will be removed in the next major version. ' +
-          'Use componentDidMount instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillMount.' +
-          '\n\nPlease update the following components: MyComponent',
-        'componentWillReceiveProps is deprecated and will be removed in the next major version. ' +
-          'Use static getDerivedStateFromProps instead.' +
-          '\n\nPlease update the following components: MyComponent',
-        'componentWillUpdate is deprecated and will be removed in the next major version. ' +
-          'Use componentDidUpdate instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillUpdate.' +
-          '\n\nPlease update the following components: MyComponent',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
diff --git a/packages/react-dom/src/__tests__/ReactDOMServerLifecycles-test.js b/packages/react-dom/src/__tests__/ReactDOMServerLifecycles-test.js
index 76230a3230350..4aed0e0246a69 100644
--- a/packages/react-dom/src/__tests__/ReactDOMServerLifecycles-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMServerLifecycles-test.js
@@ -229,7 +229,7 @@ describe('ReactDOMServerLifecycles', () => {
 
     expect(() =>
       ReactDOMServer.renderToString(<Component />),
-    ).toLowPriorityWarnDev('componentWillMount() is deprecated', {
+    ).toLowPriorityWarnDev('componentWillMount has been renamed', {
       withoutStack: true,
     });
     expect(log).toEqual(['componentWillMount', 'UNSAFE_componentWillMount']);
@@ -286,10 +286,9 @@ describe('ReactDOMServerLifecycles', () => {
 
     expect(() =>
       ReactDOMServer.renderToString(<Component />),
-    ).toLowPriorityWarnDev(
-      'Component: componentWillMount() is deprecated and will be removed in the next major version.',
-      {withoutStack: true},
-    );
+    ).toLowPriorityWarnDev('componentWillMount has been renamed', {
+      withoutStack: true,
+    });
   });
 
   it('should warn about deprecated lifecycle hooks', () => {
@@ -302,11 +301,9 @@ describe('ReactDOMServerLifecycles', () => {
 
     expect(() =>
       ReactDOMServer.renderToString(<Component />),
-    ).toLowPriorityWarnDev(
-      'Warning: Component: componentWillMount() is deprecated and will be removed ' +
-        'in the next major version.',
-      {withoutStack: true},
-    );
+    ).toLowPriorityWarnDev('componentWillMount has been renamed', {
+      withoutStack: true,
+    });
 
     // De-duped
     ReactDOMServer.renderToString(<Component />);
diff --git a/packages/react-dom/src/__tests__/ReactServerRenderingHydration-test.js b/packages/react-dom/src/__tests__/ReactServerRenderingHydration-test.js
index 38d300debd14e..d093a11bf8ab2 100644
--- a/packages/react-dom/src/__tests__/ReactServerRenderingHydration-test.js
+++ b/packages/react-dom/src/__tests__/ReactServerRenderingHydration-test.js
@@ -362,20 +362,16 @@ describe('ReactDOMServerHydration', () => {
     const element = document.createElement('div');
     expect(() => {
       element.innerHTML = ReactDOMServer.renderToString(markup);
-    }).toLowPriorityWarnDev(
-      ['componentWillMount() is deprecated and will be removed'],
-      {withoutStack: true},
-    );
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
+      withoutStack: true,
+    });
     expect(element.textContent).toBe('Hi');
 
     expect(() => {
-      expect(() => ReactDOM.hydrate(markup, element)).toWarnDev(
-        'Please update the following components to use componentDidMount instead: ComponentWithWarning',
-      );
-    }).toLowPriorityWarnDev(
-      ['componentWillMount is deprecated and will be removed'],
-      {withoutStack: true},
-    );
+      ReactDOM.hydrate(markup, element);
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
+      withoutStack: true,
+    });
     expect(element.textContent).toBe('Hi');
   });
 
diff --git a/packages/react-dom/src/server/ReactPartialRenderer.js b/packages/react-dom/src/server/ReactPartialRenderer.js
index fdc7e17b3aa1a..7e0683a153a7b 100644
--- a/packages/react-dom/src/server/ReactPartialRenderer.js
+++ b/packages/react-dom/src/server/ReactPartialRenderer.js
@@ -572,13 +572,12 @@ function resolve(
             if (!didWarnAboutDeprecatedWillMount[componentName]) {
               lowPriorityWarning(
                 false,
-                '%s: componentWillMount() is deprecated and will be ' +
-                  'removed in the next major version. Read about the motivations ' +
-                  'behind this change: ' +
-                  'https://fb.me/react-async-component-lifecycle-hooks' +
-                  '\n\n' +
-                  'As a temporary workaround, you can rename to ' +
-                  'UNSAFE_componentWillMount instead.',
+                // keep this warning in sync with ReactStrictModeWarning.js
+                'componentWillMount has been renamed, and is not recommended for use. ' +
+                  'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+                  '* Move component logic from componentWillMount into componentDidMount (preferred in most cases) ' +
+                  'or the constructor.\n' +
+                  '\nPlease update the following components: %s',
                 componentName,
               );
               didWarnAboutDeprecatedWillMount[componentName] = true;
diff --git a/packages/react-reconciler/src/ReactFiberClassComponent.js b/packages/react-reconciler/src/ReactFiberClassComponent.js
index 369b01dbca350..db35d7fe714b0 100644
--- a/packages/react-reconciler/src/ReactFiberClassComponent.js
+++ b/packages/react-reconciler/src/ReactFiberClassComponent.js
@@ -806,11 +806,6 @@ function mountClassInstance(
     }
 
     if (workInProgress.mode & StrictMode) {
-      ReactStrictModeWarnings.recordUnsafeLifecycleWarnings(
-        workInProgress,
-        instance,
-      );
-
       ReactStrictModeWarnings.recordLegacyContextWarning(
         workInProgress,
         instance,
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.js b/packages/react-reconciler/src/ReactFiberWorkLoop.js
index b05e42a5512d9..7c487d177553d 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.js
@@ -2247,7 +2247,6 @@ function checkForNestedUpdates() {
 
 function flushRenderPhaseStrictModeWarningsInDEV() {
   if (__DEV__) {
-    ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings();
     ReactStrictModeWarnings.flushLegacyContextWarning();
 
     if (warnAboutDeprecatedLifecycles) {
diff --git a/packages/react-reconciler/src/ReactStrictModeWarnings.js b/packages/react-reconciler/src/ReactStrictModeWarnings.js
index 143e7ebd4a7b9..caf989195a5de 100644
--- a/packages/react-reconciler/src/ReactStrictModeWarnings.js
+++ b/packages/react-reconciler/src/ReactStrictModeWarnings.js
@@ -16,42 +16,31 @@ import {StrictMode} from './ReactTypeOfMode';
 import lowPriorityWarning from 'shared/lowPriorityWarning';
 import warningWithoutStack from 'shared/warningWithoutStack';
 
-type LIFECYCLE =
-  | 'UNSAFE_componentWillMount'
-  | 'UNSAFE_componentWillReceiveProps'
-  | 'UNSAFE_componentWillUpdate';
-type LifecycleToComponentsMap = {[lifecycle: LIFECYCLE]: Array<Fiber>};
-type FiberToLifecycleMap = Map<Fiber, LifecycleToComponentsMap>;
 type FiberArray = Array<Fiber>;
 type FiberToFiberComponentsMap = Map<Fiber, FiberArray>;
 
 const ReactStrictModeWarnings = {
-  discardPendingWarnings(): void {},
-  flushPendingDeprecationWarnings(): void {},
-  flushPendingUnsafeLifecycleWarnings(): void {},
   recordDeprecationWarnings(fiber: Fiber, instance: any): void {},
-  recordUnsafeLifecycleWarnings(fiber: Fiber, instance: any): void {},
+  flushPendingDeprecationWarnings(): void {},
   recordLegacyContextWarning(fiber: Fiber, instance: any): void {},
   flushLegacyContextWarning(): void {},
+  discardPendingWarnings(): void {},
 };
 
 if (__DEV__) {
-  const LIFECYCLE_SUGGESTIONS = {
-    UNSAFE_componentWillMount: 'componentDidMount',
-    UNSAFE_componentWillReceiveProps: 'static getDerivedStateFromProps',
-    UNSAFE_componentWillUpdate: 'componentDidUpdate',
-  };
+  const findStrictRoot = (fiber: Fiber): Fiber | null => {
+    let maybeStrictRoot = null;
 
-  let pendingComponentWillMountWarnings: Array<Fiber> = [];
-  let pendingComponentWillReceivePropsWarnings: Array<Fiber> = [];
-  let pendingComponentWillUpdateWarnings: Array<Fiber> = [];
-  let pendingUnsafeLifecycleWarnings: FiberToLifecycleMap = new Map();
-  let pendingLegacyContextWarning: FiberToFiberComponentsMap = new Map();
+    let node = fiber;
+    while (node !== null) {
+      if (node.mode & StrictMode) {
+        maybeStrictRoot = node;
+      }
+      node = node.return;
+    }
 
-  // Tracks components we have already warned about.
-  const didWarnAboutDeprecatedLifecycles = new Set();
-  const didWarnAboutUnsafeLifecycles = new Set();
-  const didWarnAboutLegacyContext = new Set();
+    return maybeStrictRoot;
+  };
 
   const setToSortedString = set => {
     const array = [];
@@ -61,243 +50,256 @@ if (__DEV__) {
     return array.sort().join(', ');
   };
 
-  ReactStrictModeWarnings.discardPendingWarnings = () => {
-    pendingComponentWillMountWarnings = [];
-    pendingComponentWillReceivePropsWarnings = [];
-    pendingComponentWillUpdateWarnings = [];
-    pendingUnsafeLifecycleWarnings = new Map();
-    pendingLegacyContextWarning = new Map();
-  };
+  let pendingComponentWillMountWarnings: Array<Fiber> = [];
+  let pendingUNSAFE_ComponentWillMountWarnings: Array<Fiber> = [];
+  let pendingComponentWillReceivePropsWarnings: Array<Fiber> = [];
+  let pendingUNSAFE_ComponentWillReceivePropsWarnings: Array<Fiber> = [];
+  let pendingComponentWillUpdateWarnings: Array<Fiber> = [];
+  let pendingUNSAFE_ComponentWillUpdateWarnings: Array<Fiber> = [];
 
-  ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings = () => {
-    ((pendingUnsafeLifecycleWarnings: any): FiberToLifecycleMap).forEach(
-      (lifecycleWarningsMap, strictRoot) => {
-        const lifecyclesWarningMessages = [];
-
-        Object.keys(lifecycleWarningsMap).forEach(lifecycle => {
-          const lifecycleWarnings = lifecycleWarningsMap[lifecycle];
-          if (lifecycleWarnings.length > 0) {
-            const componentNames = new Set();
-            lifecycleWarnings.forEach(fiber => {
-              componentNames.add(getComponentName(fiber.type) || 'Component');
-              didWarnAboutUnsafeLifecycles.add(fiber.type);
-            });
-
-            const formatted = lifecycle.replace('UNSAFE_', '');
-            const suggestion = LIFECYCLE_SUGGESTIONS[lifecycle];
-            const sortedComponentNames = setToSortedString(componentNames);
-
-            lifecyclesWarningMessages.push(
-              `${formatted}: Please update the following components to use ` +
-                `${suggestion} instead: ${sortedComponentNames}`,
-            );
-          }
-        });
+  // Tracks components we have already warned about.
+  const didWarnAboutDeprecatedLifecycles = new Set();
 
-        if (lifecyclesWarningMessages.length > 0) {
-          const strictRootComponentStack = getStackByFiberInDevAndProd(
-            strictRoot,
-          );
-
-          warningWithoutStack(
-            false,
-            'Unsafe lifecycle methods were found within a strict-mode tree:%s' +
-              '\n\n%s' +
-              '\n\nLearn more about this warning here:' +
-              '\nhttps://fb.me/react-strict-mode-warnings',
-            strictRootComponentStack,
-            lifecyclesWarningMessages.join('\n\n'),
-          );
-        }
-      },
-    );
+  ReactStrictModeWarnings.recordDeprecationWarnings = (
+    fiber: Fiber,
+    instance: any,
+  ) => {
+    // Dedup strategy: Warn once per component.
+    if (didWarnAboutDeprecatedLifecycles.has(fiber.type)) {
+      return;
+    }
 
-    pendingUnsafeLifecycleWarnings = new Map();
-  };
+    if (
+      typeof instance.componentWillMount === 'function' &&
+      // Don't warn about react-lifecycles-compat polyfilled components.
+      instance.componentWillMount.__suppressDeprecationWarning !== true
+    ) {
+      pendingComponentWillMountWarnings.push(fiber);
+    }
 
-  const findStrictRoot = (fiber: Fiber): Fiber | null => {
-    let maybeStrictRoot = null;
+    if (
+      fiber.mode & StrictMode &&
+      typeof instance.UNSAFE_componentWillMount === 'function'
+    ) {
+      pendingUNSAFE_ComponentWillMountWarnings.push(fiber);
+    }
 
-    let node = fiber;
-    while (node !== null) {
-      if (node.mode & StrictMode) {
-        maybeStrictRoot = node;
-      }
-      node = node.return;
+    if (
+      typeof instance.componentWillReceiveProps === 'function' &&
+      instance.componentWillReceiveProps.__suppressDeprecationWarning !== true
+    ) {
+      pendingComponentWillReceivePropsWarnings.push(fiber);
     }
 
-    return maybeStrictRoot;
+    if (
+      fiber.mode & StrictMode &&
+      typeof instance.UNSAFE_componentWillReceiveProps === 'function'
+    ) {
+      pendingUNSAFE_ComponentWillReceivePropsWarnings.push(fiber);
+    }
+
+    if (
+      typeof instance.componentWillUpdate === 'function' &&
+      instance.componentWillUpdate.__suppressDeprecationWarning !== true
+    ) {
+      pendingComponentWillUpdateWarnings.push(fiber);
+    }
+
+    if (
+      fiber.mode & StrictMode &&
+      typeof instance.UNSAFE_componentWillUpdate === 'function'
+    ) {
+      pendingUNSAFE_ComponentWillUpdateWarnings.push(fiber);
+    }
   };
 
   ReactStrictModeWarnings.flushPendingDeprecationWarnings = () => {
+    // We do an initial pass to gather component names
+    const componentWillMountUniqueNames = new Set();
     if (pendingComponentWillMountWarnings.length > 0) {
-      const uniqueNames = new Set();
       pendingComponentWillMountWarnings.forEach(fiber => {
-        uniqueNames.add(getComponentName(fiber.type) || 'Component');
+        componentWillMountUniqueNames.add(
+          getComponentName(fiber.type) || 'Component',
+        );
         didWarnAboutDeprecatedLifecycles.add(fiber.type);
       });
-
-      const sortedNames = setToSortedString(uniqueNames);
-
-      lowPriorityWarning(
-        false,
-        'componentWillMount is deprecated and will be removed in the next major version. ' +
-          'Use componentDidMount instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillMount.' +
-          '\n\nPlease update the following components: %s' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-async-component-lifecycle-hooks',
-        sortedNames,
-      );
-
       pendingComponentWillMountWarnings = [];
     }
 
+    const UNSAFE_componentWillMountUniqueNames = new Set();
+    if (pendingUNSAFE_ComponentWillMountWarnings.length > 0) {
+      pendingUNSAFE_ComponentWillMountWarnings.forEach(fiber => {
+        UNSAFE_componentWillMountUniqueNames.add(
+          getComponentName(fiber.type) || 'Component',
+        );
+        didWarnAboutDeprecatedLifecycles.add(fiber.type);
+      });
+      pendingUNSAFE_ComponentWillMountWarnings = [];
+    }
+
+    const componentWillReceivePropsUniqueNames = new Set();
     if (pendingComponentWillReceivePropsWarnings.length > 0) {
-      const uniqueNames = new Set();
       pendingComponentWillReceivePropsWarnings.forEach(fiber => {
-        uniqueNames.add(getComponentName(fiber.type) || 'Component');
+        componentWillReceivePropsUniqueNames.add(
+          getComponentName(fiber.type) || 'Component',
+        );
         didWarnAboutDeprecatedLifecycles.add(fiber.type);
       });
 
-      const sortedNames = setToSortedString(uniqueNames);
+      pendingComponentWillReceivePropsWarnings = [];
+    }
 
-      lowPriorityWarning(
-        false,
-        'componentWillReceiveProps is deprecated and will be removed in the next major version. ' +
-          'Use static getDerivedStateFromProps instead.' +
-          '\n\nPlease update the following components: %s' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-async-component-lifecycle-hooks',
-        sortedNames,
-      );
+    const UNSAFE_componentWillReceivePropsUniqueNames = new Set();
+    if (pendingUNSAFE_ComponentWillReceivePropsWarnings.length > 0) {
+      pendingUNSAFE_ComponentWillReceivePropsWarnings.forEach(fiber => {
+        UNSAFE_componentWillReceivePropsUniqueNames.add(
+          getComponentName(fiber.type) || 'Component',
+        );
+        didWarnAboutDeprecatedLifecycles.add(fiber.type);
+      });
 
-      pendingComponentWillReceivePropsWarnings = [];
+      pendingUNSAFE_ComponentWillReceivePropsWarnings = [];
     }
 
+    const componentWillUpdateUniqueNames = new Set();
     if (pendingComponentWillUpdateWarnings.length > 0) {
-      const uniqueNames = new Set();
       pendingComponentWillUpdateWarnings.forEach(fiber => {
-        uniqueNames.add(getComponentName(fiber.type) || 'Component');
+        componentWillUpdateUniqueNames.add(
+          getComponentName(fiber.type) || 'Component',
+        );
         didWarnAboutDeprecatedLifecycles.add(fiber.type);
       });
 
-      const sortedNames = setToSortedString(uniqueNames);
-
-      lowPriorityWarning(
-        false,
-        'componentWillUpdate is deprecated and will be removed in the next major version. ' +
-          'Use componentDidUpdate instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillUpdate.' +
-          '\n\nPlease update the following components: %s' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-async-component-lifecycle-hooks',
-        sortedNames,
-      );
-
       pendingComponentWillUpdateWarnings = [];
     }
-  };
 
-  ReactStrictModeWarnings.recordDeprecationWarnings = (
-    fiber: Fiber,
-    instance: any,
-  ) => {
-    // Dedup strategy: Warn once per component.
-    if (didWarnAboutDeprecatedLifecycles.has(fiber.type)) {
-      return;
-    }
+    const UNSAFE_componentWillUpdateUniqueNames = new Set();
+    if (pendingUNSAFE_ComponentWillUpdateWarnings.length > 0) {
+      pendingUNSAFE_ComponentWillUpdateWarnings.forEach(fiber => {
+        UNSAFE_componentWillUpdateUniqueNames.add(
+          getComponentName(fiber.type) || 'Component',
+        );
+        didWarnAboutDeprecatedLifecycles.add(fiber.type);
+      });
 
-    // Don't warn about react-lifecycles-compat polyfilled components.
-    if (
-      typeof instance.componentWillMount === 'function' &&
-      instance.componentWillMount.__suppressDeprecationWarning !== true
-    ) {
-      pendingComponentWillMountWarnings.push(fiber);
-    }
-    if (
-      typeof instance.componentWillReceiveProps === 'function' &&
-      instance.componentWillReceiveProps.__suppressDeprecationWarning !== true
-    ) {
-      pendingComponentWillReceivePropsWarnings.push(fiber);
-    }
-    if (
-      typeof instance.componentWillUpdate === 'function' &&
-      instance.componentWillUpdate.__suppressDeprecationWarning !== true
-    ) {
-      pendingComponentWillUpdateWarnings.push(fiber);
+      pendingUNSAFE_ComponentWillUpdateWarnings = [];
     }
-  };
 
-  ReactStrictModeWarnings.recordUnsafeLifecycleWarnings = (
-    fiber: Fiber,
-    instance: any,
-  ) => {
-    const strictRoot = findStrictRoot(fiber);
-    if (strictRoot === null) {
+    // Finally, we flush all the warnings
+    // UNSAFE_ ones before the deprecated ones, since they'll be 'louder'
+    if (UNSAFE_componentWillMountUniqueNames.size > 0) {
+      const sortedNames = setToSortedString(
+        UNSAFE_componentWillMountUniqueNames,
+      );
       warningWithoutStack(
         false,
-        'Expected to find a StrictMode component in a strict mode tree. ' +
-          'This error is likely caused by a bug in React. Please file an issue.',
+        'Using UNSAFE_componentWillMount in strict mode is not recommended and may indicate bugs in your code. ' +
+          'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+          '* Move component logic from UNSAFE_componentWillMount into componentDidMount (preferred in most cases) ' +
+          'or the constructor.\n' +
+          '\nPlease update the following components: %s',
+        sortedNames,
       );
-      return;
     }
 
-    // Dedup strategy: Warn once per component.
-    // This is difficult to track any other way since component names
-    // are often vague and are likely to collide between 3rd party libraries.
-    // An expand property is probably okay to use here since it's DEV-only,
-    // and will only be set in the event of serious warnings.
-    if (didWarnAboutUnsafeLifecycles.has(fiber.type)) {
-      return;
+    if (UNSAFE_componentWillReceivePropsUniqueNames.size > 0) {
+      const sortedNames = setToSortedString(
+        UNSAFE_componentWillReceivePropsUniqueNames,
+      );
+      warningWithoutStack(
+        false,
+        'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended ' +
+          'and may indicate bugs in your code. ' +
+          'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+          '* Move data fetching logic or side effects from UNSAFE_componentWillReceiveProps ' +
+          'into componentDidUpdate.\n' +
+          "* If you're updating state whenever props change, " +
+          'move this logic into static getDerivedStateFromProps, or refactor your ' +
+          'code to use memoization techniques. ' +
+          'Learn more at: https://fb.me/react-derived-state\n' +
+          '\nPlease update the following components: %s',
+        sortedNames,
+      );
     }
 
-    let warningsForRoot;
-    if (!pendingUnsafeLifecycleWarnings.has(strictRoot)) {
-      warningsForRoot = {
-        UNSAFE_componentWillMount: [],
-        UNSAFE_componentWillReceiveProps: [],
-        UNSAFE_componentWillUpdate: [],
-      };
-
-      pendingUnsafeLifecycleWarnings.set(strictRoot, warningsForRoot);
-    } else {
-      warningsForRoot = pendingUnsafeLifecycleWarnings.get(strictRoot);
+    if (UNSAFE_componentWillUpdateUniqueNames.size > 0) {
+      const sortedNames = setToSortedString(
+        UNSAFE_componentWillUpdateUniqueNames,
+      );
+      warningWithoutStack(
+        false,
+        'Using UNSAFE_componentWillUpdate in strict mode is not recommended ' +
+          'and may indicate bugs in your code. ' +
+          'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+          '* Move data fetching logic or side effects from UNSAFE_componentWillUpdate into componentDidUpdate.\n' +
+          '\nPlease update the following components: %s',
+        sortedNames,
+      );
     }
 
-    const unsafeLifecycles = [];
-    if (
-      (typeof instance.componentWillMount === 'function' &&
-        instance.componentWillMount.__suppressDeprecationWarning !== true) ||
-      typeof instance.UNSAFE_componentWillMount === 'function'
-    ) {
-      unsafeLifecycles.push('UNSAFE_componentWillMount');
-    }
-    if (
-      (typeof instance.componentWillReceiveProps === 'function' &&
-        instance.componentWillReceiveProps.__suppressDeprecationWarning !==
-          true) ||
-      typeof instance.UNSAFE_componentWillReceiveProps === 'function'
-    ) {
-      unsafeLifecycles.push('UNSAFE_componentWillReceiveProps');
+    if (componentWillMountUniqueNames.size > 0) {
+      const sortedNames = setToSortedString(componentWillMountUniqueNames);
+
+      lowPriorityWarning(
+        false,
+        'componentWillMount has been renamed, and is not recommended for use. ' +
+          'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+          '* Move component logic from componentWillMount into componentDidMount (preferred in most cases) ' +
+          'or the constructor.\n' +
+          '* Rename componentWillMount in your code to UNSAFE_componentWillMount to suppress ' +
+          'this warning in non-strict mode. In React 17.x, only the UNSAFE_ name will work.\n' +
+          '* To rename all deprecated lifecycles to their new names, you can run ' +
+          '`npx react-codemod rename-unsafe-lifecycles /path/to/code`.\n' +
+          '\nPlease update the following components: %s',
+        sortedNames,
+      );
     }
-    if (
-      (typeof instance.componentWillUpdate === 'function' &&
-        instance.componentWillUpdate.__suppressDeprecationWarning !== true) ||
-      typeof instance.UNSAFE_componentWillUpdate === 'function'
-    ) {
-      unsafeLifecycles.push('UNSAFE_componentWillUpdate');
+
+    if (componentWillReceivePropsUniqueNames.size > 0) {
+      const sortedNames = setToSortedString(
+        componentWillReceivePropsUniqueNames,
+      );
+
+      lowPriorityWarning(
+        false,
+        'componentWillReceiveProps has been renamed, and is not recommended for use. ' +
+          'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+          '* Move data fetching logic or side effects from componentWillReceiveProps into componentDidUpdate.\n' +
+          "* If you're updating state whenever props change, refactor your " +
+          'code to use memoization techniques, or move this logic into ' +
+          'static getDerivedStateFromProps. Learn more at: https://fb.me/react-derived-state\n' +
+          '* Rename componentWillReceiveProps in your code to UNSAFE_componentWillReceiveProps to suppress ' +
+          'this warning in non-strict mode.. In React 17.x, only the UNSAFE_ name will work.\n' +
+          '* To rename all deprecated lifecycles to their new names, you can run ' +
+          '`npx react-codemod rename-unsafe-lifecycles /path/to/code`.\n' +
+          '\nPlease update the following components: %s',
+        sortedNames,
+      );
     }
 
-    if (unsafeLifecycles.length > 0) {
-      unsafeLifecycles.forEach(lifecycle => {
-        ((warningsForRoot: any): LifecycleToComponentsMap)[lifecycle].push(
-          fiber,
-        );
-      });
+    if (componentWillUpdateUniqueNames.size > 0) {
+      const sortedNames = setToSortedString(componentWillUpdateUniqueNames);
+
+      lowPriorityWarning(
+        false,
+        'componentWillUpdate has been renamed, and is not recommended for use. ' +
+          'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+          '* Move data fetching logic or side effects from componentWillUpdate into componentDidUpdate.\n' +
+          '* Rename componentWillUpdate in your code to UNSAFE_componentWillUpdate to suppress ' +
+          'this warning in non-strict mode. In React 17.x, only the UNSAFE_ name will work.\n' +
+          '* To rename all deprecated lifecycles to their new names, you can run ' +
+          '`npx react-codemod rename-unsafe-lifecycles /path/to/code`.\n' +
+          '\nPlease update the following components: %s',
+        sortedNames,
+      );
     }
   };
 
+  let pendingLegacyContextWarning: FiberToFiberComponentsMap = new Map();
+
+  // Tracks components we have already warned about.
+  const didWarnAboutLegacyContext = new Set();
+
   ReactStrictModeWarnings.recordLegacyContextWarning = (
     fiber: Fiber,
     instance: any,
@@ -358,6 +360,16 @@ if (__DEV__) {
       },
     );
   };
+
+  ReactStrictModeWarnings.discardPendingWarnings = () => {
+    pendingComponentWillMountWarnings = [];
+    pendingUNSAFE_ComponentWillMountWarnings = [];
+    pendingComponentWillReceivePropsWarnings = [];
+    pendingUNSAFE_ComponentWillReceivePropsWarnings = [];
+    pendingComponentWillUpdateWarnings = [];
+    pendingUNSAFE_ComponentWillUpdateWarnings = [];
+    pendingLegacyContextWarning = new Map();
+  };
 }
 
 export default ReactStrictModeWarnings;
diff --git a/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js
index 6557eb0b1dc88..3671f0e759f44 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js
@@ -2446,8 +2446,7 @@ describe('ReactIncremental', () => {
     ReactNoop.render(<MyComponent />);
     expect(() => expect(Scheduler).toFlushWithoutYielding()).toWarnDev(
       [
-        'componentWillReceiveProps: Please update the following components ' +
-          'to use static getDerivedStateFromProps instead: MyComponent',
+        'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended',
         'Legacy context API has been detected within a strict-mode tree: \n\n' +
           'Please update the following components: MyComponent',
       ],
@@ -2887,8 +2886,7 @@ describe('ReactIncremental', () => {
     expect(Scheduler).toFlushAndYield([]);
   });
 
-  // We don't currently use fibers as keys. Re-enable this test if we
-  // ever do again.
+  // We sometimes use Maps with Fibers as keys.
   it('does not break with a bad Map polyfill', () => {
     const realMapSet = Map.prototype.set;
 
@@ -2896,17 +2894,27 @@ describe('ReactIncremental', () => {
       function Thing() {
         throw new Error('No.');
       }
+      // This class uses legacy context, which triggers warnings,
+      // the procedures for which use a Map to store fibers.
       class Boundary extends React.Component {
         state = {didError: false};
         componentDidCatch() {
           this.setState({didError: true});
         }
+        static contextTypes = {
+          color: () => null,
+        };
         render() {
           return this.state.didError ? null : <Thing />;
         }
       }
       ReactNoop.render(<Boundary />);
-      expect(Scheduler).toFlushWithoutYielding();
+      expect(() => {
+        expect(Scheduler).toFlushWithoutYielding();
+      }).toWarnDev(
+        ['Legacy context API has been detected within a strict-mode tree'],
+        {withoutStack: true},
+      );
     }
 
     // First, verify that this code path normally receives Fibers as keys,
@@ -2952,8 +2960,11 @@ describe('ReactIncremental', () => {
     };
     React = require('react');
     ReactNoop = require('react-noop-renderer');
+    Scheduler = require('scheduler');
     try {
       triggerCodePathThatUsesFibersAsMapKeys();
+    } catch (e) {
+      throw e;
     } finally {
       // eslint-disable-next-line no-extend-native
       Map.prototype.set = realMapSet;
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js
index fb01a550a114a..b6b957647e044 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js
@@ -316,10 +316,8 @@ describe('ReactDebugFiberPerf', () => {
     addComment('Should not print a warning');
     expect(() => expect(Scheduler).toFlushWithoutYielding()).toWarnDev(
       [
-        'componentWillMount: Please update the following components ' +
-          'to use componentDidMount instead: NotCascading' +
-          '\n\ncomponentWillReceiveProps: Please update the following components ' +
-          'to use static getDerivedStateFromProps instead: NotCascading',
+        'Using UNSAFE_componentWillMount in strict mode is not recommended',
+        'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended',
       ],
       {withoutStack: true},
     );
@@ -358,14 +356,10 @@ describe('ReactDebugFiberPerf', () => {
     addComment('Mount');
     expect(() => expect(Scheduler).toFlushWithoutYielding()).toWarnDev(
       [
-        'componentWillMount: Please update the following components ' +
-          'to use componentDidMount instead: AllLifecycles' +
-          '\n\ncomponentWillReceiveProps: Please update the following components ' +
-          'to use static getDerivedStateFromProps instead: AllLifecycles' +
-          '\n\ncomponentWillUpdate: Please update the following components ' +
-          'to use componentDidUpdate instead: AllLifecycles',
-        'Legacy context API has been detected within a strict-mode tree: \n\n' +
-          'Please update the following components: AllLifecycles',
+        'Using UNSAFE_componentWillMount in strict mode is not recommended',
+        'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended',
+        'Using UNSAFE_componentWillUpdate in strict mode is not recommended',
+        'Legacy context API has been detected within a strict-mode tree',
       ],
       {withoutStack: true},
     );
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalReflection-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncrementalReflection-test.internal.js
index e161942a2986a..cf57910c7a530 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalReflection-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalReflection-test.internal.js
@@ -76,8 +76,7 @@ describe('ReactIncrementalReflection', () => {
     expect(() =>
       expect(Scheduler).toFlushAndYield(['componentDidMount: true']),
     ).toWarnDev(
-      'componentWillMount: Please update the following components ' +
-        'to use componentDidMount instead: Component',
+      'Using UNSAFE_componentWillMount in strict mode is not recommended',
       {withoutStack: true},
     );
 
@@ -116,8 +115,7 @@ describe('ReactIncrementalReflection', () => {
 
     ReactNoop.render(<Foo mount={true} />);
     expect(() => expect(Scheduler).toFlushAndYield(['Component'])).toWarnDev(
-      'componentWillMount: Please update the following components ' +
-        'to use componentDidMount instead: Component',
+      'Using UNSAFE_componentWillMount in strict mode is not recommended',
       {withoutStack: true},
     );
 
@@ -222,10 +220,10 @@ describe('ReactIncrementalReflection', () => {
     expect(() =>
       expect(Scheduler).toFlushAndYield([['componentDidMount', span()]]),
     ).toWarnDev(
-      'componentWillMount: Please update the following components ' +
-        'to use componentDidMount instead: Component' +
-        '\n\ncomponentWillUpdate: Please update the following components ' +
-        'to use componentDidUpdate instead: Component',
+      [
+        'Using UNSAFE_componentWillMount in strict mode is not recommended',
+        'Using UNSAFE_componentWillUpdate in strict mode is not recommended',
+      ],
       {withoutStack: true},
     );
 
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalUpdates-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncrementalUpdates-test.internal.js
index 58dac988901aa..ccb71f60dfbe2 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalUpdates-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalUpdates-test.internal.js
@@ -346,8 +346,7 @@ describe('ReactIncrementalUpdates', () => {
     }
     ReactNoop.render(<Foo />);
     expect(() => expect(Scheduler).toFlushWithoutYielding()).toWarnDev(
-      'componentWillReceiveProps: Please update the following components ' +
-        'to use static getDerivedStateFromProps instead: Foo',
+      'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended',
       {withoutStack: true},
     );
 
diff --git a/packages/react/src/__tests__/ReactStrictMode-test.internal.js b/packages/react/src/__tests__/ReactStrictMode-test.internal.js
index d64781dc6bcca..f1401069ccb3e 100644
--- a/packages/react/src/__tests__/ReactStrictMode-test.internal.js
+++ b/packages/react/src/__tests__/ReactStrictMode-test.internal.js
@@ -349,69 +349,10 @@ describe('ReactStrictMode', () => {
       });
       root.update(<AsyncRoot />);
       expect(() => Scheduler.unstable_flushAll()).toWarnDev(
-        'Unsafe lifecycle methods were found within a strict-mode tree:' +
-          '\n\ncomponentWillMount: Please update the following components ' +
-          'to use componentDidMount instead: AsyncRoot' +
-          '\n\ncomponentWillReceiveProps: Please update the following components ' +
-          'to use static getDerivedStateFromProps instead: Bar, Foo' +
-          '\n\ncomponentWillUpdate: Please update the following components ' +
-          'to use componentDidUpdate instead: AsyncRoot' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-strict-mode-warnings',
-        {withoutStack: true},
-      );
-
-      // Dedupe
-      root.update(<AsyncRoot />);
-      Scheduler.unstable_flushAll();
-    });
-
-    it('should coalesce warnings by lifecycle name', () => {
-      class AsyncRoot extends React.Component {
-        UNSAFE_componentWillMount() {}
-        UNSAFE_componentWillUpdate() {}
-        render() {
-          return <Parent />;
-        }
-      }
-      class Parent extends React.Component {
-        componentWillMount() {}
-        componentWillUpdate() {}
-        componentWillReceiveProps() {}
-        render() {
-          return <Child />;
-        }
-      }
-      class Child extends React.Component {
-        UNSAFE_componentWillReceiveProps() {}
-        render() {
-          return null;
-        }
-      }
-
-      const root = ReactTestRenderer.create(null, {
-        unstable_isConcurrent: true,
-      });
-      root.update(<AsyncRoot />);
-
-      expect(() => {
-        expect(() => Scheduler.unstable_flushAll()).toWarnDev(
-          'Unsafe lifecycle methods were found within a strict-mode tree:' +
-            '\n\ncomponentWillMount: Please update the following components ' +
-            'to use componentDidMount instead: AsyncRoot, Parent' +
-            '\n\ncomponentWillReceiveProps: Please update the following components ' +
-            'to use static getDerivedStateFromProps instead: Child, Parent' +
-            '\n\ncomponentWillUpdate: Please update the following components ' +
-            'to use componentDidUpdate instead: AsyncRoot, Parent' +
-            '\n\nLearn more about this warning here:' +
-            '\nhttps://fb.me/react-strict-mode-warnings',
-          {withoutStack: true},
-        );
-      }).toLowPriorityWarnDev(
         [
-          'componentWillMount is deprecated',
-          'componentWillReceiveProps is deprecated',
-          'componentWillUpdate is deprecated',
+          'Using UNSAFE_componentWillMount in strict mode is not recommended',
+          'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended',
+          'Using UNSAFE_componentWillUpdate in strict mode is not recommended',
         ],
         {withoutStack: true},
       );
@@ -445,21 +386,13 @@ describe('ReactStrictMode', () => {
       });
       root.update(<AsyncRoot foo={true} />);
       expect(() => Scheduler.unstable_flushAll()).toWarnDev(
-        'Unsafe lifecycle methods were found within a strict-mode tree:' +
-          '\n\ncomponentWillMount: Please update the following components ' +
-          'to use componentDidMount instead: Foo' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-strict-mode-warnings',
+        'Using UNSAFE_componentWillMount in strict mode is not recommended',
         {withoutStack: true},
       );
 
       root.update(<AsyncRoot foo={false} />);
       expect(() => Scheduler.unstable_flushAll()).toWarnDev(
-        'Unsafe lifecycle methods were found within a strict-mode tree:' +
-          '\n\ncomponentWillMount: Please update the following components ' +
-          'to use componentDidMount instead: Bar' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-strict-mode-warnings',
+        'Using UNSAFE_componentWillMount in strict mode is not recommended',
         {withoutStack: true},
       );
 
@@ -507,13 +440,8 @@ describe('ReactStrictMode', () => {
       }
 
       expect(() => ReactTestRenderer.create(<SyncRoot />)).toWarnDev(
-        'Unsafe lifecycle methods were found within a strict-mode tree:' +
-          '\n    in StrictMode (at **)' +
-          '\n    in SyncRoot (at **)' +
-          '\n\ncomponentWillReceiveProps: Please update the following components ' +
-          'to use static getDerivedStateFromProps instead: Bar, Foo' +
-          '\n\nLearn more about this warning here:' +
-          '\nhttps://fb.me/react-strict-mode-warnings',
+        'Using UNSAFE_componentWillReceiveProps in strict mode is not recommended',
+        {withoutStack: true},
       );
 
       // Dedupe
diff --git a/packages/react/src/__tests__/createReactClassIntegration-test.internal.js b/packages/react/src/__tests__/createReactClassIntegration-test.internal.js
index b1bd7c9b1c913..f6b7a955d5134 100644
--- a/packages/react/src/__tests__/createReactClassIntegration-test.internal.js
+++ b/packages/react/src/__tests__/createReactClassIntegration-test.internal.js
@@ -51,10 +51,7 @@ describe('create-react-class-integration', () => {
       });
 
       expect(() => ReactNative.render(<View />, 1)).toLowPriorityWarnDev(
-        'componentWillMount is deprecated and will be removed in the next major version. ' +
-          'Use componentDidMount instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillMount.' +
-          '\n\nPlease update the following components: MyNativeComponent',
+        'componentWillMount has been renamed',
         {withoutStack: true},
       );
     });
@@ -68,9 +65,7 @@ describe('create-react-class-integration', () => {
       });
 
       expect(() => ReactNative.render(<View />, 1)).toLowPriorityWarnDev(
-        'componentWillReceiveProps is deprecated and will be removed in the next major version. ' +
-          'Use static getDerivedStateFromProps instead.' +
-          '\n\nPlease update the following components: MyNativeComponent',
+        'componentWillReceiveProps has been renamed',
         {withoutStack: true},
       );
     });
diff --git a/packages/react/src/__tests__/createReactClassIntegration-test.js b/packages/react/src/__tests__/createReactClassIntegration-test.js
index 36b6bb047732b..542a35087033f 100644
--- a/packages/react/src/__tests__/createReactClassIntegration-test.js
+++ b/packages/react/src/__tests__/createReactClassIntegration-test.js
@@ -560,9 +560,9 @@ describe('create-react-class-integration', () => {
       );
     }).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -604,9 +604,9 @@ describe('create-react-class-integration', () => {
       );
     }).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -649,9 +649,9 @@ describe('create-react-class-integration', () => {
       ReactDOM.render(<Component foo="bar" />, div),
     ).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index 1e1ec36101841..f71eb8275ed9b 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -15,7 +15,7 @@ import typeof * as PersistentFeatureFlagsType from './ReactFeatureFlags.persiste
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
-export const warnAboutDeprecatedLifecycles = false;
+export const warnAboutDeprecatedLifecycles = true;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;
 export const enableSchedulerTracing = false;
diff --git a/scripts/print-warnings/print-warnings.js b/scripts/print-warnings/print-warnings.js
index db7630e9787fb..cba05817d3e82 100644
--- a/scripts/print-warnings/print-warnings.js
+++ b/scripts/print-warnings/print-warnings.js
@@ -52,8 +52,17 @@ function transform(file, enc, cb) {
 
             // warning messages can be concatenated (`+`) at runtime, so here's
             // a trivial partial evaluator that interprets the literal value
-            const warningMsgLiteral = evalToString(node.arguments[1]);
-            warnings.add(JSON.stringify(warningMsgLiteral));
+            try {
+              const warningMsgLiteral = evalToString(node.arguments[1]);
+              warnings.add(JSON.stringify(warningMsgLiteral));
+            } catch (error) {
+              console.error(
+                'Failed to extract warning message from',
+                file.path
+              );
+              console.error(astPath.node.loc);
+              throw error;
+            }
           }
         },
       },