Property '_getHostElement' does not exist on type 'MatButton' module of @angular/material/button after upgrading to angular 15

After upgrading a codebase from Angular 14 to 15, i get the following typescript error on ng serve:

Error: src/app/control-module/button/button.component.ts:35:17 - error TS2339: Property '_getHostElement' does not exist on type 'MatButton'.

35     this.button._getHostElement().classList.add('ae-btn');
                   ~~~~~~~~~~~~~~~

The faulty component looks like this:

import { Component, Input, Output, EventEmitter, ViewChild } from '@angular/core';
import { MatButton } from '@angular/material/button';

@Component({
  selector: 'ae-button',
  templateUrl: './button.component.html',
  styleUrls: ['./button.component.scss'],
})
export class Button {
  @ViewChild('btn', { static: true }) button: MatButton;
  {...}
  ngOnInit() {
    this.button._getHostElement().classList.add('ae-btn');
  }
  {...}
}

Manifest dependency changes were the following:

dependencies: 
-    "@angular/cdk": "14.2.1",
-    "@angular/common": "14.2.1",
-    "@angular/compiler": "14.2.1",
-    "@angular/material": "14.2.1",
+    "@angular/cdk": "^15.2.9",
+    "@angular/common": "^15.2.9",
+    "@angular/compiler": "^15.2.9",
+    "@angular/material": "^15.2.9",
devDependencies: 
-    "@angular-devkit/build-angular": "14.2.2",
-    "@angular-eslint/builder": "14.0.4",
-    "@angular-eslint/eslint-plugin": "14.0.4",
-    "@angular-eslint/eslint-plugin-template": "14.0.4",
-    "@angular-eslint/schematics": "14.0.4",
-    "@angular-eslint/template-parser": "14.0.4",
-    "@angular/cli": "14.2.2",
-    "@angular/compiler-cli": "14.2.1",
+    "@angular-devkit/build-angular": "^15.2.8",
+    "@angular-eslint/builder": "^15.2.1",
+    "@angular-eslint/eslint-plugin": "^15.2.1",
+    "@angular-eslint/eslint-plugin-template": "^15.2.1",
+    "@angular-eslint/schematics": "^15.2.1",
+    "@angular-eslint/template-parser": "^15.2.1",
+    "@angular/cli": "^15.2.8",
+    "@angular/compiler-cli": "^15.2.9",
-    "typescript": "4.8.3"
+    "typescript": "^4.9.5"

I don't find mention of this in bug reports/release notes, how was this changed?
Thanks!

It's not a "bug" as you described it. _getHostElement() was never a part of the public API of the MatButton in v14. All the breaking changes to the public API are either automatically handled by migration scripts, or explicitly listed in the migration docs. You can't expect internals of the component to NOT get changed. What you're doing is a rather bad practice, and it's prone to such breaking changes. In addition, directly manipulating DOM (which you are doing) is probably not a best idea either - you're better of using the Renderer2 for that.

There are other ways of getting the elementRef that don't rely on internals, e.g. using the read property on the @ViewChild decorator:

@ViewChild('btn', { static: true,  read: ElementRef}) buttonRef: ElementRef<any>;

Aside from that, there are better ways of dynamically applying classes, e.g. ngClass directive (unless you're using custom factory and can really apply those directives in the template).

If you're hellbent on retaining the previous, less reliable behavior, you can always look at the old version of the button code and look what the _getHostElement() was actually doing here:

_getHostElement() {
  return this._elementRef.nativeElement;
}

And change your code to the exactly same thing:

this.button._elementRef.nativeElement.classList.add('my-class');

Here's a working stackblitz using your @ViewChild approach.