Angular 20 + Express v5 async handlers result in a deprecation warning logged

[k-schneider]

Command

serve

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

Using async handlers with Express v5 and a freshly scaffolded Angular project results in a deprecation warning being logged:

router deprecated handlers that are Promise-like are deprecated, use a native Promise instead

Minimal Reproduction

ng new

choose "Yes" to enable SSR

In the scaffolded server.ts rewrite this:

app.use((req, res, next) => {
  angularApp
    .handle(req)
    .then((response) =>
      response ? writeResponseToNodeResponse(response, res) : next(),
    )
    .catch(next);
});

to:

app.use(async (req, res, next) => {
  try {
    const response = await angularApp.handle(req);
    if (response) {
      writeResponseToNodeResponse(response, res);
    } else {
      next();
    }
  } catch {
    next();
  }
});

Now run ng serve and open a browser to http://localhost:4200. Once the page has loaded, hit the refresh button on the browser one time and then observe the console output.

Exception or Error

router deprecated handlers that are Promise-like are deprecated, use a native Promise instead

Your Environment

Angular CLI: 20.0.4
Node: 22.12.0
Package Manager: npm 11.3.0
OS: win32 x64

Angular: 20.0.5
... common, compiler, compiler-cli, core, forms
... platform-browser, platform-server, router

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.2000.4
@angular-devkit/core         20.0.4
@angular-devkit/schematics   20.0.4
@angular/build               20.0.4
@angular/cli                 20.0.4
@angular/ssr                 20.0.4
@schematics/angular          20.0.4
rxjs                         7.8.2
typescript                   5.8.3
zone.js                      0.15.1

Anything else relevant?

No response

[alan-agius4]

This check is part of the Express router and cannot be disabled. It originates from zone.js, which patches the global Promise. In this context, the warning can be safely ignored.