Shawon Amos

Install  @angular-devkit/build-angular  as dev dependency. This package is newly introduced in Angular 6.0 npm install --save-dev @angular-devkit/build-angular or, yarn add @angular-devkit/build-angular --dev

Step 1: Find the connection’s PID > netstat - ano | findstr : yourPortNumber Then locate the PID (something like 10764) Step 2: Kill the process using it’s PID > tskill yourPID Example: tskill 10764 Step 3: Restart your server You should be able to run it (using  ng serve ) Step 4: Stop your server properly Don’t forget now to close properly your server by using  Ctrl + C  and typing  Y :