_version Previous plugin version.
	 *
	 * @return void
	 */
	public function set_option_on_update( $new_version, $old_version ) {
		$this->settings->set_option_on_update( $old_version );

		if ( version_compare( $old_version, '3.11', '>=' ) ) {
			return;
		}

		$this->database->truncate_used_css_table();
		rocket_clean_domain();
		$this->set_notice_transient();
	}

	/**
	 * Updates safelist items for new SaaS compatibility
	 *
	 * @since 3.11.0.2
	 *
	 * @param string $new_version New plugin version.
	 * @param string $old_version Previous plugin version.
	 *
	 * @return void
	 */
	public function update_safelist_items( $new_version, $old_version ) {
		$this->settings->update_safelist_items( $old_version );
	}

	/**
	 * Cancel pending jobs actions in Action Scheduler on update to 3.11.3
	 *
	 * @since 3.11.3
	 *
	 * @param string $new_version New plugin version.
	 * @param string $old_version Previous plugin version.
	 *
	 * @return void
	 */
	public function cancel_pending_jobs_as( $new_version, $old_version ) {
		if ( version_compare( $old_version, '3.11.3', '>=' ) ) {
			return;
		}

		try {
			$this->queue->cancel_pending_jobs_cron();
		} catch ( \InvalidArgumentException $e ) {
			// nothing to do.
			return;
		}
	}

	/**
	 * Sets the processing transient if RUCSS is enabled
	 *
	 * @since 3.11
	 *
	 * @param mixed $old_value Option old value.
	 * @param mixed $value     Option new value.
	 *
	 * @return void
	 */
	public function maybe_set_processing_transient( $old_value, $value ) {
		if ( ! isset( $old_value['remove_unused_css'], $value['remove_unused_css'] ) ) {
			return;
		}

		if ( 0 === (int) $value['remove_unused_css'] ) {
			return;
		}

		if ( $old_value['remove_unused_css'] === $value['remove_unused_css'] ) {
			return;
		}

		$this->set_notice_transient();
	}

	/**
	 * Sets the transient for the processing notice
	 *
	 * @since 3.11
	 *
	 * @return void
	 */
	private function set_notice_transient() {
		set_transient(
			'rocket_rucss_processing',
			time() + 90,
			1.5 * MINUTE_IN_SECONDS
		);

		rocket_renew_box( 'rucss_success_notice' );
	}

	/**
	 * Sends a request to run cron when switching to RUCSS completed notice
	 *
	 * @since 3.11
	 *
	 * @return void
	 */
	public function spawn_cron() {
		if ( rocket_get_constant( 'DISABLE_WP_CRON', false ) ) {
			return;// Bailout and don't fire the CRON.
		}

		check_ajax_referer( 'rocket-ajax', 'nonce' );

		if ( ! current_user_can( 'rocket_manage_options' ) ) {
			wp_send_json_error();
			return;
		}

		spawn_cron();

		wp_send_json_success();
	}

	/**
	 * Cancel queues and crons for RUCSS.
	 *
	 * @return void
	 */
	public function cancel_queues() {
		// Will unhook check for dispatching an async request without RUCSS process running.
		\ActionScheduler_QueueRunner::instance()->unhook_dispatch_async_request();

		// Will unhook check for dispatching an async request when RUCSS process is already running.
		RUCSSQueueRunner::instance()->unhook_dispatch_async_request();

		$this->queue->cancel_pending_jobs_cron();

		if ( ! wp_next_scheduled( 'rocket_rucss_clean_rows_time_event' ) ) {
			return;
		}

		wp_clear_scheduled_hook( 'rocket_rucss_clean_rows_time_event' );
	}

	/**
	 * Delete the transient for Action scheduler once admin visits the AS tools page.
	 *
	 * @return void
	 */
	public function delete_as_tables_transient_on_tools_page() {
		delete_transient( 'rocket_rucss_as_tables_count' );
	}

	/**
	 * Deletes the used CSS on update to 3.11.4 for new storage method
	 *
	 * @since 3.11.4
	 *
	 * @param string $new_version New plugin version.
	 * @param string $old_version Previous plugin version.
	 *
	 * @return void
	 */
	public function delete_used_css( $new_version, $old_version ) {
		if ( version_compare( $old_version, '3.11.4', '>=' ) ) {
			return;
		}

		$this->database->truncate_used_css_table();
	}

	/**
	 * Disable RUCSS on wrong license.
	 *
	 * @return bool
	 */
	public function disable_russ_on_wrong_license() {
		if ( false !== (bool) get_option( 'wp_rocket_no_licence' ) ) {
			return false;
		}
		return null;
	}

	/**
	 * Remove the resources table & version stored in options table on update to 3.12
	 *
	 * @since 3.12
	 *
	 * @param string $new_version New plugin version.
	 * @param string $old_version Previous plugin version.
	 *
	 * @return void
	 */
	public function drop_resources_table( $new_version, $old_version ) {
		if ( version_compare( $old_version, '3.12', '>=' ) ) {
			return;
		}

		$this->database->drop_resources_table();
	}

	/**
	 * Displays a notice if the used CSS folder is not writable
	 *
	 * @since 3.11.4
	 *
	 * @return void
	 */
	public function notice_write_permissions() {
		$this->used_css->notice_write_permissions();
	}

	/**
	 * Display a notice on table missing.
	 *
	 * @return void
	 */
	public function display_no_table_notice() {
		$this->settings->display_no_table_notice();
	}

	/**
	 * Maybe delete transient.
	 *
	 * @param mixed $old_value Option old value.
	 * @param mixed $value     Option new value.
	 *
	 * @return void
	 */
	public function maybe_delete_transient( $old_value, $value ) {
		if ( ! isset( $old_value['remove_unused_css'], $value['remove_unused_css'] ) ) {
			return;
		}

		if ( 1 === (int) $value['remove_unused_css'] ) {
			return;
		}

		if ( $old_value['remove_unused_css'] === $value['remove_unused_css'] ) {
			return;
		}

		delete_transient( 'wp_rocket_no_licence' );
	}

	/**
	 * Checks if the RUCSS deletion is enabled.
	 *
	 * @return bool
	 */
	protected function is_deletion_enabled(): bool {
		/**
		 * Filters the enable RUCSS deletion value
		 *
		 * @param bool $delete_rucss True to enable deletion, false otherwise.
		 */
		return (bool) apply_filters( 'rocket_rucss_deletion_enabled', true );
	}
}
<br />
<b>Fatal error</b>:  Uncaught TypeError: Argument 1 passed to WP_Rocket\Event_Management\Event_Manager::add_subscriber() must implement interface WP_Rocket\Event_Management\Subscriber_Interface, string given, called in /home/merciket/public_html/wp-content/plugins/wp-rocket/inc/Plugin.php on line 155 and defined in /home/merciket/public_html/wp-content/plugins/wp-rocket/inc/classes/event-management/class-event-manager.php:33
Stack trace:
#0 /home/merciket/public_html/wp-content/plugins/wp-rocket/inc/Plugin.php(155): WP_Rocket\Event_Management\Event_Manager-&gt;add_subscriber('WP_Rocket\\Engin...')
#1 /home/merciket/public_html/wp-content/plugins/wp-rocket/inc/main.php(42): WP_Rocket\Plugin-&gt;load()
#2 /home/merciket/public_html/wp-includes/class-wp-hook.php(324): rocket_init('')
#3 /home/merciket/public_html/wp-includes/class-wp-hook.php(348): WP_Hook-&gt;apply_filters(NULL, Array)
#4 /home/merciket/public_html/wp-includes/plugin.php(517): WP_Hook-&gt;do_action(Array)
#5 /home/merciket/public_html/wp-settings.php(506): do_action('plugins_l in <b>/home/merciket/public_html/wp-content/plugins/wp-rocket/inc/classes/event-management/class-event-manager.php</b> on line <b>33</b><br />