An error occurred: @Output not initialized

I had also the same error. I found that Auto Import extension of VS Code did this. import * as EventEmitter from 'events'; is imported instead of import { EventEmitter } from '@angular/core';

So make sure if the import is ok or not.

I had the same problem even importing from @angular/core.

The problem: I was initializing the EventEmmitter object in the ngOnInit method from my component class. Solution: I moved the initialization to the component's class constructor.

Had the same error,

Import was correct like

import { EventEmitter } from '@angular/core';

But the variable definition was wrong:

@Output() onFormChange: EventEmitter<any>;

Should be:

@Output() onFormChange: EventEmitter<any> = new EventEmitter();

To make your code work in a stackblitz, I had to replace

import { EventEmitter } from 'events';

with

import { EventEmitter } from '@angular/core';