1The error is due to missing vendor folder.
2You just need to run `composer install` in the project directory which will
3create a folder named vendor which will have all composer libraries and
4`autoload.php` file.
1There are many reasons why one might run into this error and thus a good checklist of what to check first helps considerably.
2
3Let's consider that we are troubleshooting the following line:
4
5require "/path/to/file"