From 725ae274e983b1e6e0660544332e3620e202632b Mon Sep 17 00:00:00 2001
From: eps1lon <sebastian.silbermann@vercel.com>
Date: Thu, 11 Apr 2024 22:18:31 +0200
Subject: [PATCH] fix: Improve `legacyRoot` error message

---
 src/__tests__/render.js     | 4 ++--
 src/__tests__/renderHook.js | 2 +-
 src/pure.js                 | 8 ++++++--
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/__tests__/render.js b/src/__tests__/render.js
index 16f7dbe2..192d54c6 100644
--- a/src/__tests__/render.js
+++ b/src/__tests__/render.js
@@ -234,7 +234,7 @@ describe('render API', () => {
     expect(() => {
       render(<div />, {legacyRoot: true})
     }).toThrowErrorMatchingInlineSnapshot(
-      `\`legacyRoot: true\` is not supported in this version of React. Please use React 18 instead.`,
+      `\`legacyRoot: true\` is not supported in this version of React. If your app runs React 19 or later, you should remove this flag. If your app runs React 18 or earlier, and you need help with upgrading your app, visit https://react.dev/blog/2022/03/08/react-18-upgrade-guide.`,
     )
   })
 
@@ -259,7 +259,7 @@ describe('render API', () => {
     expect(() => {
       render(ui, {container, hydrate: true, legacyRoot: true})
     }).toThrowErrorMatchingInlineSnapshot(
-      `\`legacyRoot: true\` is not supported in this version of React. Please use React 18 instead.`,
+      `\`legacyRoot: true\` is not supported in this version of React. If your app runs React 19 or later, you should remove this flag. If your app runs React 18 or earlier, and you need help with upgrading your app, visit https://react.dev/blog/2022/03/08/react-18-upgrade-guide.`,
     )
   })
 })
diff --git a/src/__tests__/renderHook.js b/src/__tests__/renderHook.js
index c7c8b066..66964de8 100644
--- a/src/__tests__/renderHook.js
+++ b/src/__tests__/renderHook.js
@@ -108,6 +108,6 @@ testGateReact19('legacyRoot throws', () => {
       },
     ).result
   }).toThrowErrorMatchingInlineSnapshot(
-    `\`legacyRoot: true\` is not supported in this version of React. Please use React 18 instead.`,
+    `\`legacyRoot: true\` is not supported in this version of React. If your app runs React 19 or later, you should remove this flag. If your app runs React 18 or earlier, and you need help with upgrading your app, visit https://react.dev/blog/2022/03/08/react-18-upgrade-guide.`,
   )
 })
diff --git a/src/pure.js b/src/pure.js
index 38ec519f..d0170748 100644
--- a/src/pure.js
+++ b/src/pure.js
@@ -209,7 +209,9 @@ function render(
 ) {
   if (legacyRoot && typeof ReactDOM.render !== 'function') {
     const error = new Error(
-      '`legacyRoot: true` is not supported in this version of React. Please use React 18 instead.',
+      '`legacyRoot: true` is not supported in this version of React. ' +
+        'If your app runs React 19 or later, you should remove this flag. ' +
+        'If your app runs React 18 or earlier, and you need help with upgrading your app, visit https://react.dev/blog/2022/03/08/react-18-upgrade-guide.',
     )
     Error.captureStackTrace(error, render)
     throw error
@@ -274,7 +276,9 @@ function renderHook(renderCallback, options = {}) {
 
   if (renderOptions.legacyRoot && typeof ReactDOM.render !== 'function') {
     const error = new Error(
-      '`legacyRoot: true` is not supported in this version of React. Please use React 18 instead.',
+      '`legacyRoot: true` is not supported in this version of React. ' +
+        'If your app runs React 19 or later, you should remove this flag. ' +
+        'If your app runs React 18 or earlier, and you need help with upgrading your app, visit https://react.dev/blog/2022/03/08/react-18-upgrade-guide.',
     )
     Error.captureStackTrace(error, renderHook)
     throw error