Warning from https://repo.packagist.org: You are using an outdated version of Composer.

 

This error occurs when i try to install vue in laravel 8.

So the error says:   

Warning from https://repo.packagist.org: You are using an outdated version of 

Composer. Composer 2 is now available and you should upgrade. See 

https://getcomposer.org/2

and when i try to install ui obviously it says:

Command "ui" is not defined. 

because it doesn't find the ui as it can't install the ui through composer.

So, To solve that,

Run:

composer self-update

then,

composer update

then, 

composer require laravel/ui

then,

php artisan ui vue

then, 

npm install

npm run dev.

For, me this solved the problem.