Ionic 4 not working in android 5

Ionic 4 apps won’t work in android 5.

When I opened in the browser also, it’s not loading. I could see the error

Uncaught SyntaxError: Use of const in strict mode.       vendor.js:71605

Ionic info output


   ionic (Ionic CLI)          : 4.1.1 (/Users/myname/.nvm/versions/node/v9.4.0/lib/node_modules/ionic)
   Ionic Framework            : @ionic/angular 4.0.0-beta.3
   @angular-devkit/core       : 0.7.4
   @angular-devkit/schematics : 0.7.4
   @angular/cli               : 6.1.5
   @ionic/ng-toolkit          : 1.0.6
   @ionic/schematics-angular  : 1.0.5


   cordova (Cordova CLI) : 8.0.0
   Cordova Platforms     : android 7.0.0, browser 5.0.4
   Cordova Plugins       : cordova-plugin-ionic-keyboard 2.1.2, cordova-plugin-ionic-webview 2.1.0, (and 4 other plugins)


   Android SDK Tools : 26.1.1 (/Users/myname/Library/Android/sdk/)
   NodeJS            : v9.4.0 (/Users/myname/.nvm/versions/node/v9.4.0/bin/node)
   npm               : 6.4.0
   OS                : macOS High Sierra

Building an android project in Ionic is a big headache. I won’t take this much time to develop.

Ionic 4 works only with android 7 plus as of my knowledge

1 Like

try to un-comment all the polyfills in polyfill.js

I tried it and that worked, thanks

Having same issue can you explain how did you solved it?
Thank you

Litterally uncommenting all the comments that are inside the file polyfills.js


 * This file includes polyfills needed by Angular and is loaded before the app.

 * You can add your own extra polyfills to this file.


 * This file is divided into 2 sections:

 *   1. Browser polyfills. These are applied before loading ZoneJS and are sorted by browsers.

 *   2. Application imports. Files imported after ZoneJS that should be loaded before your main

 *      file.


 * The current setup is for so-called "evergreen" browsers; the last versions of browsers that

 * automatically update themselves. This includes Safari >= 10, Chrome >= 55 (including Opera),

 * Edge >= 13 on the desktop, and iOS 10 and Chrome on mobile.


 * Learn more in





/** IE10 and IE11 requires the following for NgClass support on SVG elements */

// import 'classlist.js';  // Run `npm install --save classlist.js`.


 * Web Animations `@angular/platform-browser/animations`

 * Only required if AnimationBuilder is used within the application and using IE/Edge or Safari.

 * Standard animation support in Angular DOES NOT require any polyfills (as of Angular 6.0).


// import 'web-animations-js';  // Run `npm install --save web-animations-js`.


 * By default, zone.js will patch all possible macroTask and DomEvents

 * user can disable parts of macroTask/DomEvents patch by setting following flags

 * because those flags need to be set before `zone.js` being loaded, and webpack

 * will put import in the top of bundle, so user need to create a separate file

 * in this directory (for example: zone-flags.ts), and put the following flags

 * into that file, and then add the following code before importing zone.js.

 * import './zone-flags.ts';


 * The flags allowed in zone-flags.ts are listed here.


 * The following flags will work for all browsers.


 * (window as any).__Zone_disable_requestAnimationFrame = true; // disable patch requestAnimationFrame

 * (window as any).__Zone_disable_on_property = true; // disable patch onProperty such as onclick

 * (window as any).__zone_symbol__BLACK_LISTED_EVENTS = ['scroll', 'mousemove']; // disable patch specified eventNames


 *  in IE/Edge developer tools, the addEventListener will also be wrapped by zone.js

 *  with the following flag, it will bypass `zone.js` patch for IE/Edge


 *  (window as any).__Zone_enable_cross_context_check = true;



import './zone-flags.ts';


 * Zone JS is required by default for Angular itself.


import 'zone.js/dist/zone';  // Included with Angular CLI.




(window as any).global = window;

Have these lines only and tried to uncomment but didn’t worked