Fix error on 404 page when middleware exists

packages/next/src/shared/lib/router/router.ts

@@ -1456,6 +1456,8 @@ export default class Router implements BaseRouter {
       Router.events.emit('routeChangeStart', as, routeProps)
     }
 
+    const isErrorRoute = this.pathname === '/404' || this.pathname === '/_error'
+
     try {
       let routeInfo = await this.getRouteInfo({
         route,
@@ -1645,10 +1647,7 @@ export default class Router implements BaseRouter {
       // wasn't originally present. This is also why this block is before the
       // below `changeState` call which updates the browser's history (changing
       // the URL).
-      if (
-        isQueryUpdating &&
-        (this.pathname === '/404' || this.pathname === '/_error')
-      ) {
+      if (isQueryUpdating && isErrorRoute) {
         routeInfo = await this.getRouteInfo({
           route: this.pathname,
           pathname: this.pathname,
@@ -1658,6 +1657,7 @@ export default class Router implements BaseRouter {
           routeProps: { shallow: false },
           locale: nextState.locale,
           isPreview: nextState.isPreview,
+          isQueryUpdating: isQueryUpdating && !this.isFallback,
         })
 
         if ('type' in routeInfo) {

test/e2e/404-page-router/index.test.ts

@@ -118,5 +118,16 @@ describe.each(table)(
         }
       })
     })
+
+    // It should not throw any errors when re-fetching the route info:
+    // https://github.com/vercel/next.js/issues/44293
+    it('should not throw any errors when re-fetching the route info', async () => {
+      const browser = await webdriver(next.url, '/?test=1')
+      await check(
+        () => browser.eval('next.router.isReady ? "yes" : "no"'),
+        'yes'
+      )
+      expect(await browser.elementById('query').text()).toEqual('test=1')
+    })
   }
 )