SSR resolves relative `redirectTo` against the wrong base when the route path has several segments

The bug sits in resolveRedirectTo in packages/angular/ssr/src/routes/ng-routes.ts, which pops only the last segment where the router replaces all segments the route consumes. Start by reading that function, then the redirect/relative case in packages/angular/ssr/test/app_spec.ts. Done means a multi-segment relative redirectTo resolves to the router's result, with the two existing app_spec expectations updated. The issue author already has a fix and PR planned, and it changes current behaviour, so coordinate with them first.

Command

other

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

When a request matches a route with a string redirectTo, @angular/ssr answers with a 302 built from the route config, without running the router. If the route's own path has more than one segment, a relative redirectTo is resolved against the wrong base.

{ path: 'old/page', redirectTo: 'new/page' }:

• Server: GET /old/page returns Location: /old/new/page (a 404).
• Router (in-app navigation to /old/page): /new/page.

The router replaces all segments matched by the redirecting route (old/page). The server only removes the last one (page). Routes whose path is a single segment or empty are not affected, which is probably why this has gone unnoticed.

Note: fixing this changes current behaviour. app_spec.ts asserts the current result (L207-L217: redirect/relative → /redirect/home, the router gives /home), and an app could depend on it if it happens to have a route at the server-computed path.

Minimal Reproduction

npx @angular/[email protected] new repro-app --ssr --defaults
cd repro-app

src/app/app.routes.ts:

import { Component } from '@angular/core';
import { Routes } from '@angular/router';

@Component({ template: 'New page' })
class NewPage {}

export const routes: Routes = [
  { path: 'old/page', redirectTo: 'new/page' },
  { path: 'new/page', component: NewPage },
];

src/app/app.routes.server.ts (server rendering, so the request reaches the redirect handling instead of a prerendered redirect page):

import { RenderMode, ServerRoute } from '@angular/ssr';

export const serverRoutes: ServerRoute[] = [{ path: '**', renderMode: RenderMode.Server }];

npx ng build
NG_ALLOWED_HOSTS=localhost PORT=4000 node dist/repro-app/server/server.mjs
curl -si 'localhost:4000/old/page' | grep -i '^location'

Expected: location: /new/page (where the router navigates). Actual: location: /old/new/page.

Exception or Error

$ curl -si localhost:4000/old/page | head -3
HTTP/1.1 302 Found
X-Powered-By: Express
location: /old/new/page

Your Environment

     _                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/


Angular CLI       : 22.2.2
Angular           : 22.2.2
Node.js           : 24.18.0
Package Manager   : npm 11.16.0
Operating System  : linux x64

┌───────────────────────────┬───────────────────┬───────────────────┐
│ Package                   │ Installed Version │ Requested Version │
├───────────────────────────┼───────────────────┼───────────────────┤
│ @angular/build            │ 22.2.2            │ ^22.2.2           │
│ @angular/cli              │ 22.2.2            │ ^22.2.2           │
│ @angular/common           │ 22.2.2            │ ^22.2.0           │
│ @angular/compiler         │ 22.2.2            │ ^22.2.0           │
│ @angular/compiler-cli     │ 22.2.2            │ ^22.2.0           │
│ @angular/core             │ 22.2.2            │ ^22.2.0           │
│ @angular/forms            │ 22.2.2            │ ^22.2.0           │
│ @angular/platform-browser │ 22.2.2            │ ^22.2.0           │
│ @angular/platform-server  │ 22.2.2            │ ^22.2.0           │
│ @angular/router           │ 22.2.2            │ ^22.2.0           │
│ @angular/ssr              │ 22.2.2            │ ^22.2.2           │
│ rxjs                      │ 7.8.2             │ ~7.8.0            │
│ typescript                │ 6.0.3             │ ~6.0.2            │
└───────────────────────────┴───────────────────┴───────────────────┘

Anything else relevant?

resolveRedirectTo in ng-routes.ts#L543-L554 removes one segment (segments.pop()), while the router's applyRedirectCommands replaces all segments consumed by the route.

Related: #33504 / #33516 (parameters in the same function).

I have a fix with tests and will open a PR for it. It updates the two app_spec expectations above to the router's result. If the current behaviour is intended, or this should wait for a major, I'm happy to adjust.

Not browser specific. Seen with the default Express server.ts generated by ng new --ssr; the redirect comes from AngularNodeAppEngine.handle(), not from Express itself.