failed to open stream: No such file or directory in server.php on line 21 code example

Example 1: failed to open stream: No such file or directory in artisan on line 18

The error is due to missing vendor folder.
You just need to run `composer install` in the project directory which will 
create a folder named vendor which will have all composer libraries and 
`autoload.php` file.

Example 2: failed to open stream: no such file or directory php

There are many reasons why one might run into this error and thus a good checklist of what to check first helps considerably.

Let's consider that we are troubleshooting the following line:

require "/path/to/file"