Add read more link

Author: Timer

errors/react-version.md

@@ -0,0 +1,51 @@
+# Minimum React Version
+
+#### Why This Error Occurred
+
+Your project is using an old version of `react` or `react-dom` that does not
+meet the suggested minimum version requirement.
+
+Next.js suggests using, at a minimum, `react@16.10.0` and `react-dom@16.10.0`.
+Older versions of `react` and `react-dom` do work with Next.js, however, they do
+not enable all of Next.js' features.
+
+For example, the following features are not enabled with old React versions:
+
+- [Fast Refresh](https://nextjs.org/docs/basic-features/fast-refresh): instantly
+  view edits to your app without losing component state
+- Component stack trace in development: see the component tree that lead up to
+  an error
+- Hydration mismatch warnings: trace down discrepancies in your React tree that
+  cause performance problems
+
+This list is not exhaustive, but illustrative in the value of upgrading React!
+
+#### Possible Ways to Fix It
+
+**Via npm**
+
+```bash
+npm upgrade react@latest react-dom@latest
+```
+
+**Via Yarn**
+
+```bash
+yarn add react@latest react-dom@latest
+```
+
+**Manually** Open your `package.json` and upgrade `react` and `react-dom`:
+
+```json
+{
+  "dependencies": {
+    "react": "^16.10.0",
+    "react-dom": "^16.10.0"
+  }
+}
+```
+
+### Useful Links
+
+- [Fast Refresh blog post](https://nextjs.org/blog/next-9-4#fast-refresh)
+- [Fast Refresh docs](https://nextjs.org/docs/basic-features/fast-refresh)

packages/next/cli/next-dev.ts

@@ -69,7 +69,8 @@ const nextDev: cliCommand = (argv) => {
     })
     if (reactVersion && semver.lt(reactVersion, '16.10.0')) {
       Log.warn(
-        'Fast Refresh is disabled in your application due to an outdated `react` version. Please upgrade 16.10 or newer!'
+        'Fast Refresh is disabled in your application due to an outdated `react` version. Please upgrade 16.10 or newer!' +
+          ' Read more: https://err.sh/next.js/react-version'
       )
     } else {
       const reactDomVersion: string | null = await getPackageVersion({
@@ -78,7 +79,8 @@ const nextDev: cliCommand = (argv) => {
       })
       if (reactDomVersion && semver.lt(reactDomVersion, '16.10.0')) {
         Log.warn(
-          'Fast Refresh is disabled in your application due to an outdated `react-dom` version. Please upgrade 16.10 or newer!'
+          'Fast Refresh is disabled in your application due to an outdated `react-dom` version. Please upgrade 16.10 or newer!' +
+            ' Read more: https://err.sh/next.js/react-version'
         )
       }
     }