ERROR in node_modules/@angular/fire/firebase.app.module.d.ts?

Make sure you are following the version compatibility chart here

https://github.com/angular/angularfire#angular-and-firebase-versions

Do the following steps:

1. npm uninstall @angular/fire
2. npm install @angular/fire@latest

Also in your environment.ts only add below properties, avoid adding appId and measurementId (as it's there in firebase but you don't need it).

Use this command

npm i [email protected] angularfire2 --save

This incompatibility issue has been flagged on the official @angular/fire GitHub page here

The proposed workaround worked for me. In short:

1. Uninstall your current @angular/fire package (npm uninstall @angular/fire)

2. Install the latest version in development instead (6.0.4-canary.9a26fbe) with npm i @angular/[email protected] --save, as per instructions from the Maintainer here

3. Once version 6.0.4 will be out (not yet as of today), we can switch back to the latest official release. Meanwhile this should keep you going.