What best practices should be followed when handling file uploads in PHP to avoid errors like "undefined variable"?

When handling file uploads in PHP, it is important to ensure that the form containing the file input field has the correct enctype attribute set to "multipart/form-data". Additionally, always check if the file has been uploaded successfully before trying to access its properties to avoid errors like "undefined variable". 

if(isset($_FILES['file']) && $_FILES['file']['error'] === UPLOAD_ERR_OK) {
    $file_name = $_FILES['file']['name'];
    $file_size = $_FILES['file']['size'];
    $file_tmp = $_FILES['file']['tmp_name'];
    
    // Process the uploaded file
} else {
    echo "Error uploading file.";
}

Keywords

PHP file uploads error handling undefined variable $_FILES

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