Routing: redirectTo does not propagate all params in route

[IliasDewachter]

Which @angular/* package(s) are the source of the bug?

router

Is this a regression?

Yes

Description

With the following route config:

export const routes: Routes = [{
    path: ':tenantId/:projectId',
    component: JustAComponent,
    children: [
        { path: '', redirectTo: 'detail', pathMatch: 'full' },
    ],
}];

When navigating to http://localhost:4200/my-tenant/my-project, you get redirected to http://localhost:4200/my-tenant/:projectId/detail and the my-project param is gone.

This is regression that I noticed when bumping from 21.2.9 to 21.2.17.

Changing redirectTo: 'detail' to redirectTo: () => 'detail' seems to fix the issue.

Please provide a link to a minimal reproduction of the bug

https://github.com/IliasDewachter/Angular-redirectTo-bug-repro

Please provide the exception or error you saw

Please provide the environment you discovered this bug in (run ng version)

Angular CLI       : 21.2.18
Angular           : 21.2.17
Node.js           : 24.12.0
Package Manager   : npm 11.14.0
Operating System  : win32 x64

┌───────────────────────────┬───────────────────┬───────────────────┐
│ Package                   │ Installed Version │ Requested Version │
├───────────────────────────┼───────────────────┼───────────────────┤
│ @angular/build            │ 21.2.18           │ ^21.2.18          │
│ @angular/cli              │ 21.2.18           │ ^21.2.18          │
│ @angular/common           │ 21.2.17           │ ^21.2.0           │
│ @angular/compiler         │ 21.2.17           │ ^21.2.0           │
│ @angular/compiler-cli     │ 21.2.17           │ ^21.2.0           │
│ @angular/core             │ 21.2.17           │ ^21.2.0           │
│ @angular/forms            │ 21.2.17           │ ^21.2.0           │
│ @angular/platform-browser │ 21.2.17           │ ^21.2.0           │
│ @angular/platform-server  │ 21.2.17           │ ^21.2.0           │
│ @angular/router           │ 21.2.17           │ ^21.2.0           │
│ @angular/ssr              │ 21.2.18           │ ^21.2.18          │
│ rxjs                      │ 7.8.2             │ ~7.8.0            │
│ typescript                │ 5.9.3             │ ~5.9.2            │
│ vitest                    │ 4.1.10            │ ^4.0.8            │
└───────────────────────────┴───────────────────┴───────────────────┘

Anything else?

No response

[hawkgs]

Indeed, :projectId is not properly resolved in the URL. However, the same example works as expected in v22. I haven't been able to find the relevant fix on our side (yet), but have you tried updating your app to the latest version?

PS. While we appreciate minimal repro demos, it's still good to implement valid apps. In that regard, the details route is not defined nor JustAComponent has a router-outlet.

[JeanMeche]

The issue only exisit when SSR is enabled.
The regression was introduceded in @angular/ssr in 21.2.11.

[alan-agius4]

Thanks for reporting this issue. Luckily, it has already been fixed in one of the recent releases. Please update to the most recent version to resolve the problem.

If the problem persists in your application after upgrading, please open a new issue, provide a simple repository reproducing the problem, and describe the difference between the expected and current behavior. You can use ng new repro-app to create a new project where you reproduce the problem.