From 7b8f7695a7a8bfbcbae2d802e5d79289067616ff Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Markb=C3=A5ge?= <sema@fb.com>
Date: Wed, 31 Mar 2021 21:17:42 -0400
Subject: [PATCH] Ignore function and symbol values on custom-elements on the
 server (#21157)

---
 packages/react-dom/src/server/DOMMarkupOperations.js       | 7 ++++++-
 .../react-dom/src/server/ReactDOMServerFormatConfig.js     | 6 +++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/packages/react-dom/src/server/DOMMarkupOperations.js b/packages/react-dom/src/server/DOMMarkupOperations.js
index 7306d9393be56..3cddbb493e07e 100644
--- a/packages/react-dom/src/server/DOMMarkupOperations.js
+++ b/packages/react-dom/src/server/DOMMarkupOperations.js
@@ -71,7 +71,12 @@ export function createMarkupForCustomAttribute(
   name: string,
   value: mixed,
 ): string {
-  if (!isAttributeNameSafe(name) || value == null) {
+  if (
+    !isAttributeNameSafe(name) ||
+    value == null ||
+    typeof value === 'function' ||
+    typeof value === 'symbol'
+  ) {
     return '';
   }
   return name + '=' + quoteAttributeValueForBrowser(value);
diff --git a/packages/react-dom/src/server/ReactDOMServerFormatConfig.js b/packages/react-dom/src/server/ReactDOMServerFormatConfig.js
index 2a034963f48af..62f6d3ca56550 100644
--- a/packages/react-dom/src/server/ReactDOMServerFormatConfig.js
+++ b/packages/react-dom/src/server/ReactDOMServerFormatConfig.js
@@ -1070,7 +1070,11 @@ function pushStartCustomElement(
           // Ignored. These are built-in to React on the client.
           break;
         default:
-          if (isAttributeNameSafe(propKey)) {
+          if (
+            isAttributeNameSafe(propKey) &&
+            typeof propValue !== 'function' &&
+            typeof propValue !== 'symbol'
+          ) {
             target.push(
               attributeSeparator,
               stringToChunk(propKey),