Default Angular 6 (and earlier) doesn’t support Internet Explorer 11 (IE11) by default

It is actually something that was apparently planned.

In order to resolve this issue, just open polyfills.ts and uncomment the relevant section.

For me it was:

Angular (First Blood) Resources

https://cli.angular.io/ – Angular CLI

https://update.angular.io/ – a wizard for upgrading Angular Versions

https://material.angularjs.org – Angular Material (also a nice guide here: https://medium.com/@tomastrajan/the-complete-guide-to-angular-material-themes-4d165a9d24d1)