How can one effectively debug PHP scripts that involve file uploads?

When debugging PHP scripts that involve file uploads, it is important to check for common errors such as file size limitations, file type restrictions, and proper file handling. One effective way to debug file uploads is to use the $_FILES superglobal array to access information about the uploaded file and check for any errors during the upload process. 

if ($_FILES['file']['error'] > 0) {
    switch ($_FILES['file']['error']) {
        case UPLOAD_ERR_INI_SIZE:
            echo 'The uploaded file exceeds the upload_max_filesize directive in php.ini';
            break;
        case UPLOAD_ERR_FORM_SIZE:
            echo 'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form';
            break;
        case UPLOAD_ERR_PARTIAL:
            echo 'The uploaded file was only partially uploaded';
            break;
        case UPLOAD_ERR_NO_FILE:
            echo 'No file was uploaded';
            break;
        case UPLOAD_ERR_NO_TMP_DIR:
            echo 'Missing a temporary folder';
            break;
        case UPLOAD_ERR_CANT_WRITE:
            echo 'Failed to write file to disk';
            break;
        case UPLOAD_ERR_EXTENSION:
            echo 'A PHP extension stopped the file upload';
            break;
        default:
            echo 'Unknown upload error';
            break;
    }
}

Keywords

PHP file uploads debugging error handling $_FILES

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