What are common issues when trying to create an upload script in PHP?

One common issue when creating an upload script in PHP is insufficient file upload size limits set in the php.ini configuration file. To solve this, you can increase the `upload_max_filesize` and `post_max_size` values in the php.ini file or override them in your PHP script using `ini_set()`.

// Increase file upload size limits in PHP script
ini_set('upload_max_filesize', '20M');
ini_set('post_max_size', '25M');