public function handle_upload() {
		// phpcs:disable WordPress.Security.NonceVerification.Missing -- Nonce already verified in WC_Product_CSV_Importer_Controller::upload_form_handler()
		$file_url = isset( $_POST['file_url'] ) ? wc_clean( wp_unslash( $_POST['file_url'] ) ) : '';

		if ( empty( $file_url ) ) {
			if ( ! isset( $_FILES['import'] ) ) {
				return new WP_Error( 'woocommerce_product_csv_importer_upload_file_empty', __( 'File is empty. Please upload something more substantial. This error could also be caused by uploads being disabled in your php.ini or by post_max_size being defined as smaller than upload_max_filesize in php.ini.', 'woocommerce' ) );
			}

			// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotValidated
			if ( ! self::is_file_valid_csv( wc_clean( wp_unslash( $_FILES['import']['name'] ) ), false ) ) {
				return new WP_Error( 'woocommerce_product_csv_importer_upload_file_invalid', __( 'Invalid file type. The importer supports CSV and TXT file formats.', 'woocommerce' ) );
			}

			$overrides = array(
				'test_form' => false,
				'mimes'     => self::get_valid_csv_filetypes(),
			);
			$import    = $_FILES['import']; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized,WordPress.Security.ValidatedSanitizedInput.MissingUnslash
			$upload    = wp_handle_upload( $import, $overrides );

			if ( isset( $upload['error'] ) ) {
				return new WP_Error( 'woocommerce_product_csv_importer_upload_error', $upload['error'] );
			}

			// Construct the object array.
			$object = array(
				'post_title'     => basename( $upload['file'] ),
				'post_content'   => $upload['url'],
				'post_mime_type' => $upload['type'],
				'guid'           => $upload['url'],
				'context'        => 'import',
				'post_status'    => 'private',
			);

			// Save the data.
			$id = wp_insert_attachment( $object, $upload['file'] );

			/*
			 * Schedule a cleanup for one day from now in case of failed
			 * import or missing wp_import_cleanup() call.
			 */
			wp_schedule_single_event( time() + DAY_IN_SECONDS, 'importer_scheduled_cleanup', array( $id ) );

			return $upload['file'];
		} elseif ( file_exists( ABSPATH . $file_url ) ) {
			if ( ! self::is_file_valid_csv( ABSPATH . $file_url ) ) {
				return new WP_Error( 'woocommerce_product_csv_importer_upload_file_invalid', __( 'Invalid file type. The importer supports CSV and TXT file formats.', 'woocommerce' ) );
			}

			return ABSPATH . $file_url;
		}
		// phpcs:enable

		return new WP_Error( 'woocommerce_product_csv_importer_upload_invalid_file', __( 'Please upload or provide the link to a valid CSV file.', 'woocommerce' ) );
	}