Updates the value of a network option that was already added.

function update_network_option( $network_id, $option, $value ) {
	global $wpdb;

	if ( $network_id && ! is_numeric( $network_id ) ) {
		return false;
	}

	$network_id = (int) $network_id;

	// Fallback to the current network if a network ID is not specified.
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	wp_protect_special_option( $option );

	$old_value = get_network_option( $network_id, $option, false );

	/**
	 * Filters a specific network option before its value is updated.
	 *
	 * The dynamic portion of the hook name, `$option`, refers to the option name.
	 *
	 * @since 2.9.0 As 'pre_update_site_option_' . $key
	 * @since 3.0.0
	 * @since 4.4.0 The `$option` parameter was added.
	 * @since 4.7.0 The `$network_id` parameter was added.
	 *
	 * @param mixed  $value      New value of the network option.
	 * @param mixed  $old_value  Old value of the network option.
	 * @param string $option     Option name.
	 * @param int    $network_id ID of the network.
	 */
	$value = apply_filters( "pre_update_site_option_{$option}", $value, $old_value, $option, $network_id );

	/*
	 * If the new and old values are the same, no need to update.
	 *
	 * Unserialized values will be adequate in most cases. If the unserialized
	 * data differs, the (maybe) serialized data is checked to avoid
	 * unnecessary database calls for otherwise identical object instances.
	 *
	 * See https://core.trac.wordpress.org/ticket/44956
	 */
	if ( $value === $old_value || maybe_serialize( $value ) === maybe_serialize( $old_value ) ) {
		return false;
	}

	if ( false === $old_value ) {
		return add_network_option( $network_id, $option, $value );
	}

	$notoptions_key = "$network_id:notoptions";
	$notoptions     = wp_cache_get( $notoptions_key, 'site-options' );

	if ( is_array( $notoptions ) && isset( $notoptions[ $option ] ) ) {
		unset( $notoptions[ $option ] );
		wp_cache_set( $notoptions_key, $notoptions, 'site-options' );
	}

	if ( ! is_multisite() ) {
		$result = update_option( $option, $value, 'no' );
	} else {
		$value = sanitize_option( $option, $value );

		$serialized_value = maybe_serialize( $value );
		$result           = $wpdb->update(
			$wpdb->sitemeta,
			array( 'meta_value' => $serialized_value ),
			array(
				'site_id'  => $network_id,
				'meta_key' => $option,
			)
		);

		if ( $result ) {
			$cache_key = "$network_id:$option";
			wp_cache_set( $cache_key, $value, 'site-options' );
		}
	}

	if ( $result ) {

		/**
		 * Fires after the value of a specific network option has been successfully updated.
		 *
		 * The dynamic portion of the hook name, `$option`, refers to the option name.
		 *
		 * @since 2.9.0 As "update_site_option_{$key}"
		 * @since 3.0.0
		 * @since 4.7.0 The `$network_id` parameter was added.
		 *
		 * @param string $option     Name of the network option.
		 * @param mixed  $value      Current value of the network option.
		 * @param mixed  $old_value  Old value of the network option.
		 * @param int    $network_id ID of the network.
		 */
		do_action( "update_site_option_{$option}", $option, $value, $old_value, $network_id );

		/**
		 * Fires after the value of a network option has been successfully updated.
		 *
		 * @since 3.0.0
		 * @since 4.7.0 The `$network_id` parameter was added.
		 *
		 * @param string $option     Name of the network option.
		 * @param mixed  $value      Current value of the network option.
		 * @param mixed  $old_value  Old value of the network option.
		 * @param int    $network_id ID of the network.
		 */
		do_action( 'update_site_option', $option, $value, $old_value, $network_id );

		return true;
	}

	return false;
}