auth does not exist on type angular fire module code example

Example: property 'auth' does not exist on type 'angularfireauth' angular

1 - npm uninstall firebase @angular/fire

2- package.json

3 - dependencies { ... "@angular/fire": "6.0.0", "firebase": "7.14.1", ... }

4 - change

dependencies { ... "@angular/fire": "^5.4.2",

    ...
5 - save

6 - npm install firebase @angular/fire

if you find another much better solution but for now this worked