diff --git a/packages/react-reconciler/src/ReactFiberThrow.new.js b/packages/react-reconciler/src/ReactFiberThrow.new.js
index 78e88f125a1aa..85728d96bb730 100644
--- a/packages/react-reconciler/src/ReactFiberThrow.new.js
+++ b/packages/react-reconciler/src/ReactFiberThrow.new.js
@@ -474,7 +474,8 @@ function throwException(
       return;
     } else {
       // No boundary was found. Fallthrough to error mode.
-      // TODO: Use invariant so the message is stripped in prod?
+      // TODO: We should never call getComponentNameFromFiber in production.
+      // Log a warning or something to prevent us from accidentally bundling it.
       value = new Error(
         (getComponentNameFromFiber(sourceFiber) || 'A React component') +
           ' suspended while rendering, but no fallback UI was specified.\n' +
diff --git a/packages/react-reconciler/src/ReactFiberThrow.old.js b/packages/react-reconciler/src/ReactFiberThrow.old.js
index d2d39793a3bc0..27b0719ba8532 100644
--- a/packages/react-reconciler/src/ReactFiberThrow.old.js
+++ b/packages/react-reconciler/src/ReactFiberThrow.old.js
@@ -474,7 +474,8 @@ function throwException(
       return;
     } else {
       // No boundary was found. Fallthrough to error mode.
-      // TODO: Use invariant so the message is stripped in prod?
+      // TODO: We should never call getComponentNameFromFiber in production.
+      // Log a warning or something to prevent us from accidentally bundling it.
       value = new Error(
         (getComponentNameFromFiber(sourceFiber) || 'A React component') +
           ' suspended while rendering, but no fallback UI was specified.\n' +
diff --git a/scripts/error-codes/codes.json b/scripts/error-codes/codes.json
index 3c5f3d75a16eb..d11735986235a 100644
--- a/scripts/error-codes/codes.json
+++ b/scripts/error-codes/codes.json
@@ -394,5 +394,6 @@
   "405": "hydrateRoot(...): Target container is not a DOM element.",
   "406": "act(...) is not supported in production builds of React.",
   "407": "Missing getServerSnapshot, which is required for server-rendered content. Will revert to client rendering.",
-  "408": "Missing getServerSnapshot, which is required for server-rendered content."
+  "408": "Missing getServerSnapshot, which is required for server-rendered content.",
+  "409": "%s suspended while rendering, but no fallback UI was specified.\n\nAdd a <Suspense fallback=...> component higher in the tree to provide a loading indicator or placeholder to display."
 }