What is the common issue with including files in PHP scripts on a web server?

The common issue with including files in PHP scripts on a web server is that the file paths may not be correctly specified, leading to errors in including the files. To solve this issue, it is recommended to use absolute file paths or relative paths based on the location of the current script.

// Using absolute file path
include_once('/path/to/include/file.php');

// Using relative file path
include_once(__DIR__ . '/relative/path/to/include/file.php');