Composer throws [ReflectionException] Class Fxp\Composer\AssetPlugin\Repository\NpmRepository does not exist

Question

I installed the latest version (1.0.0. stable) of composer and in my Yii2 project I typed this:

php composer.phar update

It gives me this error

Answer 1

About nine days ago (around end of March, 2016), Composer\Repository\ComposerRepository::whatProvides api changed. (#2668) So, if you have installed fxp/composer-asset-plugin globally, you should update it. You can do that with:

php composer.phar global update fxp/composer-asset-plugin --no-plugins