From d8395e4eeba8e7114c0c5463ea2c016e5fced1ac Mon Sep 17 00:00:00 2001
From: Damien Simonin Feugas <damien@vercel.com>
Date: Thu, 13 Oct 2022 20:03:10 +0200
Subject: [PATCH] docs: more detailed error message when failing to parse a
 middleware matcher (#41390)
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## 📖 What's in there?

This is a follow-up for https://github.com/vercel/next.js/pull/40180
Someone made the good point that users may get directed to this error page while setting up middleware matchers. And that page has no information (yet) about it.

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm lint`
- [x] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)



Co-authored-by: Balázs Orbán <18369201+balazsorban44@users.noreply.github.com>
---
 errors/invalid-route-source.md | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/errors/invalid-route-source.md b/errors/invalid-route-source.md
index c29c8610cf65c..0995c5714b5d1 100644
--- a/errors/invalid-route-source.md
+++ b/errors/invalid-route-source.md
@@ -2,12 +2,18 @@
 
 #### Why This Error Occurred
 
-When defining custom routes a route was added that causes an error during parsing. This can be due to trying to use normal `RegExp` syntax like negative lookaheads (`?!exclude`) without following `path-to-regexp`'s syntax for it.
+When defining custom routes, or a middleware `matcher`, a pattern could not be parsed.
+
+This could have been due to trying to use normal `RegExp` syntax like negative lookaheads (`?!exclude`) without following [`path-to-regexp`](https://github.com/pillarjs/path-to-regexp)'s syntax for it.
 
 #### Possible Ways to Fix It
 
 Wrap the `RegExp` part of your `source` as an un-named parameter.
 
+---
+
+Custom routes:
+
 **Before**
 
 ```js
@@ -26,6 +32,26 @@ Wrap the `RegExp` part of your `source` as an un-named parameter.
 }
 ```
 
+---
+
+Middleware:
+
+**Before**
+
+```js
+const config = {
+  matcher: '/feedback/(?!general)',
+}
+```
+
+**After**
+
+```js
+const config = {
+  matcher: '/feedback/((?!general).*)',
+}
+```
+
 ### Useful Links
 
 - [path-to-regexp](https://github.com/pillarjs/path-to-regexp)