When trying to use Angular 2.0 (beta) in Visual Studio 2015, the TypeScript compiler generated the following error message: Error TS2664 Invalid module name in augmentation, module '../../Observable' cannot be found. Here is the package.json I was using: The problem seems to be related to the combination of the RxJs and Angular version I was using. To fix it, I had to change the RxJs version from "rxjs": "5.0.0-beta.4" to "rxjs": "5.0.0-beta.2" After NPM installed the correct packages, the TypeScript error disappeared.