# Build Prod failed. Could not find cordova.js script tag. Plugin loading may fail

**URL:** <https://forum.ionicframework.com/t/build-prod-failed-could-not-find-cordova-js-script-tag-plugin-loading-may-fail/207436>\
**Category:** Ionic Angular\
**Created:** [March 31, 2021, 10:12am UTC](https://forum.ionicframework.com/t/build-prod-failed-could-not-find-cordova-js-script-tag-plugin-loading-may-fail/207436 "2021-03-31T10:12:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![anton\_klochko](https://avatars.discourse-cdn.com/v4/letter/a/d78d45/32.png) [@anton\_klochko](https://forum.ionicframework.com/u/anton_klochko)\
**Post date:** [March 31, 2021, 10:12am UTC](https://forum.ionicframework.com/t/build-prod-failed-could-not-find-cordova-js-script-tag-plugin-loading-may-fail/207436/1 "2021-03-31T10:12:07Z")

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Could anyone suggest please, what is going wrong ? When I am running **ionic cordova build ios --prod**

I see white screen with errors…

> TypeError: undefined is not a constructor (evaluating ‘new o.BehaviorSubject(!1)’)
> 
> Could not find cordova.js script tag. Plugin loading may fail.

But if I am running

**ionic cordova build ios** … everything is ok.

Ionic info:

> Ionic:
> 
> Ionic CLI : 6.12.4 (/usr/local/lib/node\_modules/@ionic/cli)  
> Ionic Framework : @ionic/angular 5.5.2  
> @angular-devkit/build-angular : 0.1000.8  
> @angular-devkit/schematics : 10.0.8  
> @angular/cli : 10.0.8  
> @ionic/angular-toolkit : 2.3.3
> 
> Cordova:
> 
> Cordova CLI : 10.0.0  
> Cordova Platforms : none  
> Cordova Plugins : no whitelisted plugins (0 plugins total)
> 
> Utility:
> 
> cordova-res : not installed  
> native-run : not installed
> 
> System:
> 
> ios-deploy : 1.11.3  
> ios-sim : 8.0.2  
> NodeJS : v14.15.4 (/usr/local/bin/node)  
> npm : 6.14.10  
> OS : macOS Big Sur  
> Xcode : Xcode 12.4 Build version 12D4e

---

<div class="post-metadata">

**Author:** ![anton\_klochko](https://avatars.discourse-cdn.com/v4/letter/a/d78d45/32.png) [@anton\_klochko](https://forum.ionicframework.com/u/anton_klochko)\
**Post date:** [March 31, 2021, 10:42am UTC](https://forum.ionicframework.com/t/build-prod-failed-could-not-find-cordova-js-script-tag-plugin-loading-may-fail/207436/2 "2021-03-31T10:42:37Z")

</div>

problem solved. Change import { BehaviorSubject } from ‘rxjs’;