diff --git a/packages/react-devtools-core/src/standalone.js b/packages/react-devtools-core/src/standalone.js
index c04cad1ddea08..6b598efa22442 100644
--- a/packages/react-devtools-core/src/standalone.js
+++ b/packages/react-devtools-core/src/standalone.js
@@ -11,7 +11,7 @@ import {createElement} from 'react';
 import {
   // $FlowFixMe Flow does not yet know about flushSync()
   flushSync,
-} from 'react-dom/client';
+} from 'react-dom';
 import {createRoot} from 'react-dom/client';
 import Bridge from 'react-devtools-shared/src/bridge';
 import Store from 'react-devtools-shared/src/devtools/store';
@@ -106,9 +106,9 @@ function safeUnmount() {
   flushSync(() => {
     if (root !== null) {
       root.unmount();
+      root = null;
     }
   });
-  root = null;
 }
 
 function reload() {
diff --git a/packages/react-devtools-shared/src/bridge.js b/packages/react-devtools-shared/src/bridge.js
index ecb5e66672de8..0e5f837ecbc78 100644
--- a/packages/react-devtools-shared/src/bridge.js
+++ b/packages/react-devtools-shared/src/bridge.js
@@ -54,6 +54,9 @@ export const BRIDGE_PROTOCOL: Array<BridgeProtocol> = [
     minNpmVersion: '"<4.11.0"',
     maxNpmVersion: '"<4.11.0"',
   },
+  // Versions 4.11.x – 4.12.x contained the backwards breaking change,
+  // but we didn't add the "fix" of checking the protocol version until 4.13,
+  // so we don't recommend downgrading to 4.11 or 4.12.
   {
     version: 1,
     minNpmVersion: '4.13.0',
diff --git a/packages/react-devtools-shared/src/devtools/store.js b/packages/react-devtools-shared/src/devtools/store.js
index ddf647cc210fa..f172cd6aa306b 100644
--- a/packages/react-devtools-shared/src/devtools/store.js
+++ b/packages/react-devtools-shared/src/devtools/store.js
@@ -180,7 +180,8 @@ export default class Store extends EventEmitter<{|
   _rootSupportsBasicProfiling: boolean = false;
   _rootSupportsTimelineProfiling: boolean = false;
 
-  _unsupportedBridgeProtocol: BridgeProtocol | null = null;
+  _bridgeProtocol: BridgeProtocol | null = null;
+  _unsupportedBridgeProtocolDetected: boolean = false;
   _unsupportedRendererVersionDetected: boolean = false;
 
   // Total number of visible elements (within all roots).
@@ -375,6 +376,10 @@ export default class Store extends EventEmitter<{|
     this.emit('componentFilters');
   }
 
+  get bridgeProtocol(): BridgeProtocol | null {
+    return this._bridgeProtocol;
+  }
+
   get errorCount(): number {
     return this._cachedErrorCount;
   }
@@ -466,8 +471,8 @@ export default class Store extends EventEmitter<{|
     return this._supportsTraceUpdates;
   }
 
-  get unsupportedBridgeProtocol(): BridgeProtocol | null {
-    return this._unsupportedBridgeProtocol;
+  get unsupportedBridgeProtocolDetected(): boolean {
+    return this._unsupportedBridgeProtocolDetected;
   }
 
   get unsupportedRendererVersionDetected(): boolean {
@@ -942,11 +947,21 @@ export default class Store extends EventEmitter<{|
               (operations[i] & PROFILING_FLAG_TIMELINE_SUPPORT) !== 0;
             i++;
 
-            const supportsStrictMode = operations[i] > 0;
-            i++;
+            let supportsStrictMode = false;
+            let hasOwnerMetadata = false;
 
-            const hasOwnerMetadata = operations[i] > 0;
-            i++;
+            // If we don't know the bridge protocol, guess that we're dealing with the latest.
+            // If we do know it, we can take it into consideration when parsing operations.
+            if (
+              this._bridgeProtocol === null ||
+              this._bridgeProtocol.version >= 2
+            ) {
+              supportsStrictMode = operations[i] > 0;
+              i++;
+
+              hasOwnerMetadata = operations[i] > 0;
+              i++;
+            }
 
             this._roots = this._roots.concat(id);
             this._rootIDToRendererID.set(id, rendererID);
@@ -1383,14 +1398,13 @@ export default class Store extends EventEmitter<{|
       this._onBridgeProtocolTimeoutID = null;
     }
 
+    this._bridgeProtocol = bridgeProtocol;
+
     if (bridgeProtocol.version !== currentBridgeProtocol.version) {
-      this._unsupportedBridgeProtocol = bridgeProtocol;
-    } else {
-      // If we should happen to get a response after timing out...
-      this._unsupportedBridgeProtocol = null;
+      // Technically newer versions of the frontend can, at least for now,
+      // gracefully handle older versions of the backend protocol.
+      // So for now we don't need to display the unsupported dialog.
     }
-
-    this.emit('unsupportedBridgeProtocolDetected');
   };
 
   onBridgeProtocolTimeout = () => {
@@ -1398,7 +1412,7 @@ export default class Store extends EventEmitter<{|
 
     // If we timed out, that indicates the backend predates the bridge protocol,
     // so we can set a fake version (0) to trigger the downgrade message.
-    this._unsupportedBridgeProtocol = BRIDGE_PROTOCOL[0];
+    this._bridgeProtocol = BRIDGE_PROTOCOL[0];
 
     this.emit('unsupportedBridgeProtocolDetected');
   };
diff --git a/packages/react-devtools-shared/src/devtools/views/UnsupportedBridgeProtocolDialog.js b/packages/react-devtools-shared/src/devtools/views/UnsupportedBridgeProtocolDialog.js
index d48ab40aa3ea7..05f41c6211e75 100644
--- a/packages/react-devtools-shared/src/devtools/views/UnsupportedBridgeProtocolDialog.js
+++ b/packages/react-devtools-shared/src/devtools/views/UnsupportedBridgeProtocolDialog.js
@@ -33,20 +33,18 @@ export default function UnsupportedBridgeProtocolDialog(_: {||}) {
   useEffect(() => {
     const updateDialog = () => {
       if (!isVisible) {
-        if (store.unsupportedBridgeProtocol !== null) {
+        if (store.unsupportedBridgeProtocolDetected) {
           dispatch({
             canBeDismissed: false,
             id: MODAL_DIALOG_ID,
             type: 'SHOW',
             content: (
-              <DialogContent
-                unsupportedBridgeProtocol={store.unsupportedBridgeProtocol}
-              />
+              <DialogContent unsupportedBridgeProtocol={store.bridgeProtocol} />
             ),
           });
         }
       } else {
-        if (store.unsupportedBridgeProtocol === null) {
+        if (!store.unsupportedBridgeProtocolDetected) {
           dispatch({
             type: 'HIDE',
             id: MODAL_DIALOG_ID,
diff --git a/packages/react-devtools-shared/src/devtools/views/hooks.js b/packages/react-devtools-shared/src/devtools/views/hooks.js
index 1a34373fc7e19..897bc928cb0a1 100644
--- a/packages/react-devtools-shared/src/devtools/views/hooks.js
+++ b/packages/react-devtools-shared/src/devtools/views/hooks.js
@@ -239,10 +239,13 @@ export function useModalDismissSignal(
       // It's important to listen to the ownerDocument to support the browser extension.
       // Here we use portals to render individual tabs (e.g. Profiler),
       // and the root document might belong to a different window.
-      ownerDocument = ((modalRef.current: any): HTMLDivElement).ownerDocument;
-      ownerDocument.addEventListener('keydown', handleDocumentKeyDown);
-      if (dismissOnClickOutside) {
-        ownerDocument.addEventListener('click', handleDocumentClick, true);
+      const div = modalRef.current;
+      if (div != null) {
+        ownerDocument = div.ownerDocument;
+        ownerDocument.addEventListener('keydown', handleDocumentKeyDown);
+        if (dismissOnClickOutside) {
+          ownerDocument.addEventListener('click', handleDocumentClick, true);
+        }
       }
     }, 0);