From 8bf10dbca566f4832f4327d81107ce3f27b26d4f Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Tue, 27 Jul 2021 14:10:20 -0500
Subject: [PATCH 1/2] Document i18n locale limit

---
 docs/advanced-features/i18n-routing.md | 5 +++++
 packages/next/server/config.ts         | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/docs/advanced-features/i18n-routing.md b/docs/advanced-features/i18n-routing.md
index c21b2b9e73d67..5932f80d77461 100644
--- a/docs/advanced-features/i18n-routing.md
+++ b/docs/advanced-features/i18n-routing.md
@@ -281,3 +281,8 @@ export const getStaticPaths = ({ locales }) => {
   }
 }
 ```
+
+## Limits for the i18n config
+
+- `locales`: 100 total locales
+- `domains`: 100 total locale domain items
diff --git a/packages/next/server/config.ts b/packages/next/server/config.ts
index fae751e863a78..9919ca951703e 100644
--- a/packages/next/server/config.ts
+++ b/packages/next/server/config.ts
@@ -320,6 +320,12 @@ function assignDefaults(userConfig: { [key: string]: any }) {
       )
     }
 
+    if (i18n.locales.length > 100) {
+      throw new Error(
+        `Received ${i18n.locales.length} i18n.locales items which exceeds the max of 100, please reduce the number of items to continue.\nSee more info here: https://nextjs.org/docs/messages/invalid-i18n-config`
+      )
+    }
+
     const defaultLocaleType = typeof i18n.defaultLocale
 
     if (!i18n.defaultLocale || defaultLocaleType !== 'string') {

From f8d6ace93dede703151b5d9cc0e0f125d6c0a796 Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Tue, 27 Jul 2021 14:17:45 -0500
Subject: [PATCH 2/2] mention limit in error doc

---
 errors/invalid-i18n-config.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/errors/invalid-i18n-config.md b/errors/invalid-i18n-config.md
index 1a1be32af8839..b840d14a61f98 100644
--- a/errors/invalid-i18n-config.md
+++ b/errors/invalid-i18n-config.md
@@ -2,11 +2,11 @@
 
 #### Why This Error
 
-In your `next.config.js` file you provided an invalid config for the `i18n` field.
+In your `next.config.js` file you provided an invalid config for the `i18n` field. This could mean the limit for 100 locale items was exceeded.
 
 #### Possible Ways to Fix It
 
-Make sure your `i18n` field follows the allowed config shape and values:
+Make sure your `i18n` field follows the allowed config shape, limits, and values:
 
 ```js
 module.exports = {