This tutorial shows you how to fix "Could not find Angular Material core theme. Most Material components may not work as expected. For more info refer to the theming guide" when using angular material.
To solve the problem "could not find angular material core theme angular 2,3,4,5,6,7" you can insert below code into your style.css which is located in your src folder.
or add css directly to the index.html
<link href="node_modules/@angular/material/prebuilt-themes/indigo-pink.css" rel="stylesheet">
I hope so you can solve the problem "could not find angular material core theme scss".