Module federation not working on angular 20

[smil-thakur]

With what library do you have an issue?

module-federation

Reproduction of the bug/regression with instructions

When adding Module Federation to a new Angular 20 project using
ng add @angular-architects/module-federation and building the app with npx ng build, the build completes successfully.

However, when serving the built application via index.html, the app fails at runtime with an RxJS error related to extending a null class.

This issue occurs on a freshly created Angular 20 project with no additional changes beyond adding Module Federation.

TypeError: Class extends value undefined is not a constructor or null
at 1687 (OperatorSubscriber.js:5:41)
at webpack_require (bootstrap:19:1)
at 3481 (EmptyError.js:6:1)
at webpack_require (bootstrap:19:1)
at 4982 (timer.js:33:1)
at webpack_require (bootstrap:19:1)
at 1340 (catchError.js:26:1)
at webpack_require (bootstrap:19:1)
at sharing:48:1
at webpack_require.m. (main.378a84abe5572df5.js:1:10312)

Expected behavior

It should load the host Frontend with all chunks and no error

Versions of Native/Module Federation, Angular, Node, Browser, and operating system

Module Federation : 20
Angular : 20
Node: 24
Browser : chrome / edge
OS: Windows

Other information

Angular CLI: 20.3.15
Node: 24.13.0
Package Manager: npm 11.6.2
OS: linux x64

Angular: 20.3.16
... common, compiler, compiler-cli, core, forms
... platform-browser, router

Package Version

@angular-devkit/architect 0.2003.15
@angular-devkit/build-angular 20.3.15
@angular-devkit/core 20.3.15
@angular-devkit/schematics 20.3.15
@angular/build 20.3.15
@angular/cli 20.3.15
@schematics/angular 20.3.15
rxjs 7.8.2
typescript 5.9.3
zone.js 0.15.1

I would be willing to submit a PR to fix this issue

• Yes
• No

[sergiucristianstanciu]

Hi @smil-thakur ,
Just wanted to confirm that I have the same issue using the exact same tech stack.
Does anyone know if there are some workarounds for this?
Or maybe upgrading to Angular v21 could be a solution? (Kind of doubt it since v20 is broken).

[smil-thakur]

Hi @smil-thakur ,
Just wanted to confirm that I have the same issue using the exact same tech stack.
Does anyone know if there are some workarounds for this?
Or maybe upgrading to Angular v21 could be a solution? (Kind of doubt it since v20 is broken).

Since we were not able to find any concrete solution we are shifting to native federation but we would love to know the root cause and proper solution on module federation

[Robin-Bley]

Hi together, today a new release was published for module-federation. Maybe it solves your problem.

[sergiucristianstanciu]

one thing that worked for me and acts like a workaround was this addition to the webpack.config.js
module.exports.optimization = { ...module.exports.optimization, concatenateModules: false, };

With concatenateModules: false, each module keeps its own function wrapper and explicit dependency resolution. The cost is a slight increase in bundle size from the extra function wrappers. For my specific scenario was a jump from 699kb to 700kb so nothing major.

Maybe this helps another fellow developer in need.

[leo2823]

Hi everyone, it is a Webpack problem fixed in v 5.105.0. Look at this issue. You need to update to the last patch of Angular 21 to get this Webpack version.