Error : Data path "" must NOT have additional properties(styleext). Solution: In the angular.json file change from "styleext": "scss" to "style": "scss" Error: More than one module matches. Use the skip-import option to skip importing the component into the closest module or use the module option to specify a module. Solution: ng generate component componentname--module app or ng g c componentname --module app Error: Could not find module "@angular-devkit/build-angular" when issuing the command ng serve Solution 1 : ng update Solution 2 : First delete the node_modules and issue these commands npm install & npm update Solution 3 : npm install --save-dev @angular-devkit/build-angular@latest