When I'd switched to Angular4.0.0-rc.1 I got an error during the build (npm start):
ERROR in Could not resolve module @angular/router/src/router_config_loader
Is it known issue?
This is the solution from: Cannot Upgrade a Existing Angular Cli project to Angular 4 Rc1
npm install @angular/common@next --save
npm install @angular/compiler@next --save
npm install @angular/compiler-cli@next --save
npm install @angular/core@next --save
npm install @angular/forms@next --save
npm install @angular/http@next --save
npm install @angular/platform-browser@next --save
npm install @angular/platform-browser-dynamic@next --save
npm install @angular/platform-server@next --save
npm install @angular/router@next --save
npm install @angular/animations@next --save