[Bug] Production build with optimization enabled breaks UI styles/scripts (Angular 20 + Ionic 8)

[tomasthesandbox]

Command

build

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

18

Description

I am encountering a critical issue when building my Ionic 8 / Angular 20 application for production using the default optimization settings.

The build process completes successfully without errors. However, when deploying the application, the UI appears broken (styles are not applied correctly or components are not rendering), even though the browser network tab shows all JS and CSS files loading with 200 OK and the browser console is completely empty (no errors).

Minimal Reproduction

Steps to Reproduce:

1. Create a new Ionic/Angular project (or use an existing one with the versions below).
2. Run ionic build --configuration production (which uses @angular-devkit/build-angular with optimization: true).
3. Deploy to a static host or serve the www folder.
4. Open the app in the browser.

Current Behavior: The app loads, but styles/scripts seem corrupted or ignored. The UI is broken (missing styles, interactive elements not working). No errors in the console.

Expected Behavior: The app should look and behave exactly like in the development environment (ionic serve).

Workaround: The only way to fix this was to disable optimization in angular.json for the production configuration:

"optimization": false

OR specifically disabling the build optimizer (if applicable to the schema).

Conclusion: It seems like the build optimizer / minifier in Angular CLI 20 is generating silent corruptions when paired with this specific stack, which prevents the browser from applying the code correctly despite successful download.

Exception or Error

Your Environment

Environment:
- OS: Windows (o tu SO actual)
- Node: v20.19.5
- NPM: 10.8.2
- Angular CLI: 20.3.4
- @ionic/angular: ^8.0.0
- @angular-devkit/build-angular: ^20.0.0

Anything else relevant?

No response

[alan-agius4]

This seems like a bug but we'll need to look at a reproduction to find and fix the problem. Can you setup a minimal repro please?

You can read here why this is needed. A good way to make a minimal repro is to create a new app via ng new repro-app and adding the minimum possible code to show the problem. Then you can push this repository to github and link it here.

This might be related to your directory structure so its really important to get an accurate repro to diagnose this.

[tomasthesandbox]

Hello, Thank you for the quick response. I attempted to create a minimal reproduction using ng new repro-app with the same version stack (Angular 20 + Ionic 8), but unfortunately, *I was unable to reproduce the issue in a clean/blank application.* The fresh app compiles and runs correctly in production mode. The issue is currently isolated to my large private project. Since I cannot share the entire repository code, I am sharing the specific configuration context that triggers the bug. *Key Observation:* The critical symptom is that setting "optimization": false (or specifically disabling scripts/styles optimization) in angular.json *completely resolves the issue*. This strongly suggests a conflict within the build optimizer or minification process when handling the specific combination of dependencies I am using. To assist in diagnosing potential conflicts, I have attached/linked my *package.json* and *angular.json*. *Suspected Environment:* - *Angular CLI:* 20.3.4 - *Ionic:* 8.0.0 - *Node:* v20.19.5 - *Build Result:* Network returns status 200 for JS/CSS files, Console is clean (no errors), but UI styles/logic are not applied unless optimization is disabled. I hope this configuration data helps pinpoint if a specific library (e.g., moment, swiper, etc.) or a specific build target is causing the optimizer to generate corrupt output. Best regards, Tomás.

[alan-agius4]

@tomasthesandbox, there is not files attached, however without a runnable reproduction it's unlikely that we'll be able to action this.

[alan-agius4]

Thanks for reporting this issue. However, you didn't provide sufficient information for us to understand and reproduce the problem. Please check out our submission guidelines to understand why we can't act on issues that are lacking important information.

If the problem persists, please file a new issue and ensure you provide all of the required information when filling out the issue template.