Finally fixed it, just followed the steps on the UPGRADE.md doc
If you are using Composer to upgrade Yii, you should run the following command first (once for all) to install the composer-asset-plugin:
composer global require "fxp/composer-asset-plugin:^1.2.0"
(See http://www.yiiframework.com/doc-2.0/guide-start-installation.html#installing-from-composer for latest version.)
You may also need to add the following code to your project’s composer.json
file :
"extra": {
"asset-installer-paths": {
"npm-asset-library": "vendor/npm",
"bower-asset-library": "vendor/bower"
}
}
Hopes this helps 🙂