How can one troubleshoot and resolve issues with PHP scripts not being able to upload files to a server?

Issue: If PHP scripts are unable to upload files to a server, it may be due to incorrect file permissions, insufficient upload_max_filesize or post_max_size settings in php.ini, or errors in the PHP script itself. To resolve this issue, ensure that the file permissions are set correctly, increase the upload_max_filesize and post_max_size settings in php.ini if needed, and double-check the PHP script for any errors.

// Example PHP script to upload a file to the server
if ($_FILES['file']['error'] === UPLOAD_ERR_OK) {
    $uploadDir = 'uploads/';
    $uploadFile = $uploadDir . basename($_FILES['file']['name']);

    if (move_uploaded_file($_FILES['file']['tmp_name'], $uploadFile)) {
        echo "File uploaded successfully.";
    } else {
        echo "Error uploading file.";
    }
} else {
    echo "File upload error: " . $_FILES['file']['error'];
}