diff --git a/CHANGELOG.md b/CHANGELOG.md
index 81aac7f40f..095296dba2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,7 +23,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fix [#1767](https://github.com/Microsoft/BotFramework-WebChat/issues/1767). Remove `cursor: pointer` from buttons, by [@corinagum](https://github.com/corinagum) in PR [#1819](https://github.com/Microsoft/BotFramework-WebChat/pull/1819)
 - Fix [#1774](https://github.com/Microsoft/BotFramework-WebChat/issues/1774). Add `styleSetOption` to allow word break. Default to `break-word`, by [@corinagum](https://github.com/corinagum) in PR [#1832](https://github.com/Microsoft/BotFramework-WebChat/pull/1832)
 - Fix [#1847](https://github.com/Microsoft/BotFramework-WebChat/issues/1847). Bump react-say, which adds babel-runtime dependency, by [@corinagum](https://github.com/corinagum) in PR [#1849](https://github.com/Microsoft/BotFramework-WebChat/pull/1849)
+- Add [#1524](https://github.com/Microsoft/BotFramework-WebChat/issues/1524) Offline UI connecting for the first time, by [@corinagum](https://github.com/corinagum), in PR [#1866](https://github.com/Microsoft/BotFramework-WebChat/pull/1866)
 - Fix [#1768](https://github.com/Microsoft/BotFramework-WebChat/issues/1768). Add style option to modify all Send Box borders, by [@corinagum](https://github.com/corinagum) in PR [#1871](https://github.com/Microsoft/BotFramework-WebChat/pull/1871)
+- Fix [#1827](https://github.com/Microsoft/BotFramework-WebChat/issues/1827). Remove renderer for unknown activities, by [@corinagum](https://github.com/corinagum) in PR [#1873](https://github.com/Microsoft/BotFramework-WebChat/pull/1873)
 
 ## [4.3.0] - 2019-03-04
 
@@ -42,7 +44,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - `component`: Allow root component height and width customization via `styleOptions.rootHeight` and `styleOptions.rootWidth`, by [@tonyanziano](https://github.com/tonyanziano), in PR [#1702](https://github.com/Microsoft/BotFramework-WebChat/pull/1702)
 - `component`: Added `cardActionMiddleware` to customize the behavior of card action, by [@compulim](https://github.com/compulim), in PR [#1704](https://github.com/Microsoft/BotFramework-WebChat/pull/1704)
 - `bundle`: Add `watermark` and `streamUrl` parameters to createDirectLine, by [@corinagum](https://github.com/corinagum), in PR [#1817](https://github.com/Microsoft/BotFramework-WebChat/pull/1817)
-- Add [#1523](https://github.com/Microsoft/BotFramework-WebChat/issues/1523) Offline UI connecting for the first time, by [@corinagum](https://github.com/corinagum), in PR [#1866](https://github.com/Microsoft/BotFramework-WebChat/pull/1866)
 
 ### Changed
 
diff --git a/__tests__/__image_snapshots__/chrome-docker/basic-js-unknown-activities-do-not-render-anything-in-the-transcript-1-snap.png b/__tests__/__image_snapshots__/chrome-docker/basic-js-unknown-activities-do-not-render-anything-in-the-transcript-1-snap.png
new file mode 100644
index 0000000000..4e037412da
Binary files /dev/null and b/__tests__/__image_snapshots__/chrome-docker/basic-js-unknown-activities-do-not-render-anything-in-the-transcript-1-snap.png differ
diff --git a/__tests__/basic.js b/__tests__/basic.js
index 81b64f2fbb..b9914c2ffc 100644
--- a/__tests__/basic.js
+++ b/__tests__/basic.js
@@ -7,64 +7,76 @@ import uiConnected from './setup/conditions/uiConnected';
 // selenium-webdriver API doc:
 // https://seleniumhq.github.io/selenium/docs/api/javascript/module/selenium-webdriver/index_exports_WebDriver.html
 
-jest.setTimeout(timeouts.test);
+jest.setTimeout( timeouts.test );
 
-test('setup', async () => {
+test( 'setup', async () => {
   const { driver, pageObjects } = await setupWebDriver();
 
-  await driver.wait(uiConnected(), timeouts.directLine);
-  await pageObjects.sendMessageViaSendBox('layout carousel');
+  await driver.wait( uiConnected(), timeouts.directLine );
+  await pageObjects.sendMessageViaSendBox( 'layout carousel' );
 
-  await driver.wait(minNumActivitiesShown(2), 2000);
-  await driver.wait(allImagesLoaded(), 2000);
+  await driver.wait( minNumActivitiesShown( 2 ), 2000 );
+  await driver.wait( allImagesLoaded(), 2000 );
 
   const base64PNG = await driver.takeScreenshot();
 
-  expect(base64PNG).toMatchImageSnapshot(imageSnapshotOptions);
-});
+  expect( base64PNG ).toMatchImageSnapshot( imageSnapshotOptions );
+} );
 
-test('long URLs with break-word', async () => {
-  const { driver, pageObjects} = await setupWebDriver();
+test( 'long URLs with break-word', async () => {
+  const { driver, pageObjects } = await setupWebDriver();
 
-  await driver.wait(uiConnected(), timeouts.directLine);
-  await pageObjects.sendMessageViaSendBox('https://subdomain.domain.com/pathname0/pathname1/pathname2/pathname3/pathname4/')
+  await driver.wait( uiConnected(), timeouts.directLine );
+  await pageObjects.sendMessageViaSendBox( 'https://subdomain.domain.com/pathname0/pathname1/pathname2/pathname3/pathname4/' )
 
-  await driver.wait(minNumActivitiesShown(2), 2000);
-  await driver.wait(allImagesLoaded(), 2000);
+  await driver.wait( minNumActivitiesShown( 2 ), 2000 );
+  await driver.wait( allImagesLoaded(), 2000 );
 
   const base64PNG = await driver.takeScreenshot();
 
-  expect(base64PNG).toMatchImageSnapshot(imageSnapshotOptions);
-});
+  expect( base64PNG ).toMatchImageSnapshot( imageSnapshotOptions );
+} );
 
-test('long URLs with break-all', async () => {
+test( 'long URLs with break-all', async () => {
   const WEB_CHAT_PROPS = { styleOptions: { messageActivityWordBreak: 'break-all' } };
 
-  const { driver, pageObjects} = await setupWebDriver({ props: WEB_CHAT_PROPS });
+  const { driver, pageObjects } = await setupWebDriver( { props: WEB_CHAT_PROPS } );
 
-  await driver.wait(uiConnected(), timeouts.directLine);
-  await pageObjects.sendMessageViaSendBox('https://subdomain.domain.com/pathname0/pathname1/pathname2/pathname3/pathname4/')
+  await driver.wait( uiConnected(), timeouts.directLine );
+  await pageObjects.sendMessageViaSendBox( 'https://subdomain.domain.com/pathname0/pathname1/pathname2/pathname3/pathname4/' )
 
-  await driver.wait(minNumActivitiesShown(2), 2000);
-  await driver.wait(allImagesLoaded(), 2000);
+  await driver.wait( minNumActivitiesShown( 2 ), 2000 );
+  await driver.wait( allImagesLoaded(), 2000 );
 
   const base64PNG = await driver.takeScreenshot();
 
-  expect(base64PNG).toMatchImageSnapshot(imageSnapshotOptions);
-});
+  expect( base64PNG ).toMatchImageSnapshot( imageSnapshotOptions );
+} );
 
-test('long URLs with keep-all', async () => {
+test( 'long URLs with keep-all', async () => {
   const WEB_CHAT_PROPS = { styleOptions: { messageActivityWordBreak: 'keep-all' } };
 
-  const { driver, pageObjects} = await setupWebDriver({ props: WEB_CHAT_PROPS });
+  const { driver, pageObjects } = await setupWebDriver( { props: WEB_CHAT_PROPS } );
+
+  await pageObjects.sendMessageViaSendBox( '箸より重いものを持ったことがない箸より重いものを持ったことがない' );
+
+  await driver.wait( minNumActivitiesShown( 2 ), 2000 );
+  await driver.wait( allImagesLoaded(), 2000 );
+
+  const base64PNG = await driver.takeScreenshot();
+
+  expect( base64PNG ).toMatchImageSnapshot( imageSnapshotOptions );
+} );
+
+test( 'unknown activities do not render anything in the transcript', async () => {
+  const { driver, pageObjects } = await setupWebDriver();
 
-  await driver.wait(uiConnected(), timeouts.directLine);
-  await pageObjects.sendMessageViaSendBox('箸より重いものを持ったことがない箸より重いものを持ったことがない')
+  await driver.wait( uiConnected(), timeouts.directLine );
+  await pageObjects.sendMessageViaSendBox( 'unknown activity' );
 
-  await driver.wait(minNumActivitiesShown(2), 2000);
-  await driver.wait(allImagesLoaded(), 2000);
+  await driver.wait( minNumActivitiesShown( 1 ), 2000 );
 
   const base64PNG = await driver.takeScreenshot();
 
-  expect(base64PNG).toMatchImageSnapshot(imageSnapshotOptions);
-});
+  expect( base64PNG ).toMatchImageSnapshot( imageSnapshotOptions );
+} );
diff --git a/packages/component/src/BasicWebChat.js b/packages/component/src/BasicWebChat.js
index 53c8ec618b..6911dc8a48 100644
--- a/packages/component/src/BasicWebChat.js
+++ b/packages/component/src/BasicWebChat.js
@@ -11,86 +11,83 @@ import createCoreAttachmentMiddleware from './Middleware/Attachment/createCoreMi
 import ErrorBox from './ErrorBox';
 import TypeFocusSinkBox from './Utils/TypeFocusSink';
 
-const ROOT_CSS = css({
+const ROOT_CSS = css( {
   display: 'flex',
   flexDirection: 'column'
-});
+} );
 
-const TRANSCRIPT_CSS = css({
+const TRANSCRIPT_CSS = css( {
   flex: 1
-});
+} );
 
-const SEND_BOX_CSS = css({
+const SEND_BOX_CSS = css( {
   flexShrink: 0
-});
+} );
 
 export default class extends React.Component {
-  constructor(props) {
-    super(props);
+  constructor( props ) {
+    super( props );
 
     this.sendBoxRef = React.createRef();
 
     this.state = {
-      activityRenderer: this.createActivityRenderer(props.activityMiddleware),
-      attachmentRenderer: this.createAttachmentRenderer(props.attachmentMiddleware)
+      activityRenderer: this.createActivityRenderer( props.activityMiddleware ),
+      attachmentRenderer: this.createAttachmentRenderer( props.attachmentMiddleware )
     };
   }
 
   // TODO: [P2] Move to React 16 APIs
-  componentWillReceiveProps({ activityMiddleware, attachmentMiddleware }) {
+  componentWillReceiveProps( { activityMiddleware, attachmentMiddleware } ) {
     if (
       this.props.activityMiddleware !== activityMiddleware
       || this.props.attachmentMiddleware !== attachmentMiddleware
     ) {
-      this.setState(() => ({
-        activityRenderer: this.createActivityRenderer(activityMiddleware),
-        attachmentRenderer: this.createAttachmentRenderer(attachmentMiddleware)
-      }));
+      this.setState( () => ( {
+        activityRenderer: this.createActivityRenderer( activityMiddleware ),
+        attachmentRenderer: this.createAttachmentRenderer( attachmentMiddleware )
+      } ) );
     }
   }
 
-  createActivityRenderer(additionalMiddleware) {
+  createActivityRenderer( additionalMiddleware ) {
     const activityMiddleware = concatMiddleware(
       additionalMiddleware,
       createCoreActivityMiddleware()
-    )({});
+    )( {} );
 
-    return (...args) => {
+    return ( ...args ) => {
       try {
         return activityMiddleware(
-          ({ activity }) => () =>
-            <ErrorBox message="No renderer for this activity">
-              <pre>{ JSON.stringify(activity, null, 2) }</pre>
-            </ErrorBox>
-        )(...args);
-      } catch (err) {
+          ( { activity } ) => () => console.log( activity )
+        )( ...args );
+      } catch ( err ) {
         return () => (
           <ErrorBox message="Failed to render activity">
-            <pre>{ JSON.stringify(err, null, 2) }</pre>
+            <pre>{JSON.stringify( err, null, 2 )}</pre>
           </ErrorBox>
         );
       }
     };
   }
 
-  createAttachmentRenderer(additionalMiddleware) {
+  createAttachmentRenderer( additionalMiddleware ) {
     const attachmentMiddleware = concatMiddleware(
       additionalMiddleware,
       createCoreAttachmentMiddleware()
-    )({});
+    )( {} );
 
-    return (...args) => {
+    return ( ...args ) => {
       try {
         return attachmentMiddleware(
-          ({ attachment }) =>
+          ( { attachment } ) =>
             <ErrorBox message="No renderer for this attachment">
-              <pre>{ JSON.stringify(attachment, null, 2) }</pre>
+              <pre>{JSON.stringify( attachment, null, 2 )}</pre>
             </ErrorBox>
-        )(...args);
-      } catch (err) {
+        )( ...args );
+      } catch ( err ) {
         return (
           <ErrorBox message="Failed to render attachment">
-            <pre>{ JSON.stringify(err, null, 2) }</pre>
+            <pre>{JSON.stringify( err, null, 2 )}</pre>
           </ErrorBox>
         );
       }
@@ -104,20 +101,20 @@ export default class extends React.Component {
 
     return (
       <Composer
-        activityRenderer={ state.activityRenderer }
-        attachmentRenderer={ state.attachmentRenderer }
-        sendBoxRef={ this.sendBoxRef }
-        { ...props }
+        activityRenderer={state.activityRenderer}
+        attachmentRenderer={state.attachmentRenderer}
+        sendBoxRef={this.sendBoxRef}
+        {...props}
       >
-        { ({ styleSet }) =>
+        {( { styleSet } ) =>
           <TypeFocusSinkBox
-            className={ classNames(ROOT_CSS + '', styleSet.root + '', (props.className || '') + '') }
+            className={classNames( ROOT_CSS + '', styleSet.root + '', ( props.className || '' ) + '' )}
             role="complementary"
-            sendFocusRef={ this.sendBoxRef }
+            sendFocusRef={this.sendBoxRef}
           >
-            <BasicTranscript className={ TRANSCRIPT_CSS + '' } />
-            { !styleSet.options.hideSendBox &&
-              <BasicSendBox className={ SEND_BOX_CSS } />
+            <BasicTranscript className={TRANSCRIPT_CSS + ''} />
+            {!styleSet.options.hideSendBox &&
+              <BasicSendBox className={SEND_BOX_CSS} />
             }
           </TypeFocusSinkBox>
         }