SSG generates empty index.html if navigation in guard

[Schoko19961]

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

platform-server

Is this a regression?

Yes

Description

Latest working version: 20.3.6

If a route that's configured to be prerendered, contains a guard which navigates somewhere else, ssg generates an empty index.html

In the reproduction:

• When a user navigates to /subroute he should be navigated to /subroute/subsub
• No error message or hint that this is happening is thrown

Workaround:

• disable the guard when platform is server

Please provide a link to a minimal reproduction of the bug

https://github.com/Schoko19961/angular-ssg-empty-index-html

Please provide the exception or error you saw

No exception or warning was logged

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

Angular CLI: 20.3.7
Node: 22.20.0
Package Manager: npm 10.9.3
OS: linux x64
    

Angular: 20.3.7
... build, cli, common, compiler, compiler-cli, core, forms
... platform-browser, platform-server, router, ssr

Package                      Version
------------------------------------
@angular-devkit/architect    0.2003.7
@angular-devkit/core         20.3.7
@angular-devkit/schematics   20.3.7
@schematics/angular          20.3.7
rxjs                         7.8.2
typescript                   5.9.3
zone.js                      0.15.1

Anything else?

No response