require(vendor/autoload.php): failed to open stream

Question

I know that this issue has been posted many times, but for me it seems to be a different problem.

Indeed, this error

Warning: require(vendor/autol

Answer 1

Create composer.json file with requisite library for ex:

{
    "require": {
        "mpdf/mpdf": "^6.1"
    }
}

Execute the below command where composer.json exists:

composer install

In case of Drupal :

Use the web root folder of drupal to include autoload for ex:

define('DRUPAL_ROOT', getcwd());
require_once DRUPAL_ROOT . '/vendor/autoload.php';

In case of other systems: Use the root folder variable or location to include the autoload.php