angular · atscott · Aug 29, 2025
diff --git a/packages/core/test/bundling/router/bundle.golden_symbols.json b/packages/core/test/bundling/router/bundle.golden_symbols.json
@@ -621,6 +621,7 @@
       "fireActivationStart",
       "fireChildActivationStart",
       "first",
+      "firstValueFrom",
       "flatten",
       "flattenRouteTree",
       "forEachSingleProvider",

diff --git a/packages/router/src/apply_redirects.ts b/packages/router/src/apply_redirects.ts
@@ -16,6 +16,7 @@ import {ActivatedRouteSnapshot} from './router_state';
 import {Params, PRIMARY_OUTLET} from './shared';
 import {UrlSegment, UrlSegmentGroup, UrlSerializer, UrlTree} from './url_tree';
 import {wrapIntoObservable} from './utils/collection';
+import {firstValueFrom} from './utils/first_value_from';
 
 export const NO_MATCH_ERROR_NAME = 'ɵNoMatch';
 export class NoMatch extends Error {
@@ -195,9 +196,11 @@ function getRedirectResult(
   }
   const redirectToFn = redirectTo;
   const {queryParams, fragment, routeConfig, url, outlet, params, data, title} = currentSnapshot;
-  return wrapIntoObservable(
-    runInInjectionContext(injector, () =>
-      redirectToFn({params, data, queryParams, fragment, routeConfig, url, outlet, title}),
+  return firstValueFrom(
+    wrapIntoObservable(
+      runInInjectionContext(injector, () =>
+        redirectToFn({params, data, queryParams, fragment, routeConfig, url, outlet, title}),
+      ),
     ),
-  ).toPromise() as Promise<string | UrlTree>;
+  );
 }
diff --git a/packages/router/src/recognize.ts b/packages/router/src/recognize.ts
@@ -38,6 +38,7 @@ import {
   split,
 } from './utils/config_matching';
 import {TreeNode} from './utils/tree';
+import {firstValueFrom} from './utils/first_value_from';
 
 /**
  * Class used to indicate there were no additional route config matches but that all segments of
@@ -400,14 +401,9 @@ export class Recognizer {
     if (this.abortSignal.aborted) {
       throw new Error(this.abortSignal.reason);
     }
-    const result = await matchWithChecks(
-      rawSegment,
-      route,
-      segments,
-      injector,
-      this.urlSerializer,
-      this.abortSignal,
-    ).toPromise();
+    const result = await firstValueFrom(
+      matchWithChecks(rawSegment, route, segments, injector, this.urlSerializer, this.abortSignal),
+    );
     if (route.path === '**') {
       // Prior versions of the route matching algorithm would stop matching at the wildcard route.
       // We should investigate a better strategy for any existing children. Otherwise, these
@@ -500,15 +496,11 @@ export class Recognizer {
       if (this.abortSignal.aborted) {
         throw new Error(this.abortSignal.reason);
       }
-      const shouldLoadResult = await runCanLoadGuards(
-        injector,
-        route,
-        segments,
-        this.urlSerializer,
-        this.abortSignal,
-      ).toPromise();
+      const shouldLoadResult = await firstValueFrom(
+        runCanLoadGuards(injector, route, segments, this.urlSerializer, this.abortSignal),
+      );
       if (shouldLoadResult) {
-        const cfg = await this.configLoader.loadChildren(injector, route).toPromise();
+        const cfg = await firstValueFrom(this.configLoader.loadChildren(injector, route));
         if (!cfg) {
           throw canLoadFails(route);
         }

diff --git a/packages/router/src/utils/first_value_from.ts b/packages/router/src/utils/first_value_from.ts
@@ -0,0 +1,20 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import {Observable} from 'rxjs';
+import {first} from 'rxjs/operators';
+
+/** replacement for firstValueFrom in rxjs 7. We must support rxjs v6 so we cannot use it */
+export function firstValueFrom<T>(source: Observable<T>): Promise<T> {
+  return new Promise<T>((resolve, reject) => {
+    source.pipe(first()).subscribe({
+      next: (value) => resolve(value),
+      error: (err) => reject(err),
+    });
+  });
+}
diff --git a/packages/router/test/apply_redirects.spec.ts b/packages/router/test/apply_redirects.spec.ts
@@ -8,8 +8,8 @@
 
 import {EnvironmentInjector, inject, Injectable, Type} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
-import {firstValueFrom, Observable, of} from 'rxjs';
-import {switchMap, tap} from 'rxjs/operators';
+import {firstValueFrom, interval, Observable, of} from 'rxjs';
+import {map, switchMap, tap} from 'rxjs/operators';
 
 import {Route, Routes} from '../src/models';
 import {recognize} from '../src/recognize';
@@ -1819,6 +1819,27 @@ describe('redirects', () => {
         },
       );
     });
+
+    it('works when the returned redirect observable does not complete', async () => {
+      await checkRedirect(
+        [
+          {
+            path: 'a',
+            children: [
+              {
+                path: 'b',
+                redirectTo: () => interval(100).pipe(map(() => '/redirected')),
+              },
+            ],
+          },
+          {path: '**', component: ComponentC},
+        ],
+        '/a;k1=v1;k2=v2/b;k3=v3;k4=v4',
+        (t: UrlTree) => {
+          expectTreeToBe(t, 'redirected');
+        },
+      );
+    });
   });
 
   // internal failure b/165719418