diff --git a/includes/admin/class-general-admin-notices.php b/includes/admin/class-general-admin-notices.php
index d264638..c265f00 100644
--- a/includes/admin/class-general-admin-notices.php
+++ b/includes/admin/class-general-admin-notices.php
@@ -1,8 +1,8 @@
 <?php
 /**
- * Class responsible for Event Plugin related admin notices.
+ * Class responsible for general admin notices.
  *
- * Notices for guiding to proper configuration of ActivityPub with event plugins.
+ * Notices for guiding to proper configuration of this plugin.
  *
  * @package Activitypub_Event_Extensions
  * @since 1.0.0
@@ -11,45 +11,61 @@
 namespace Activitypub_Event_Extensions\Admin;
 
 /**
- * Class responsible for Event Plugin related admin notices.
+ * Class responsible for general admin notices.
  *
- * Notices for guiding to proper configuration of ActivityPub with event plugins.
+ * Notices for guiding to proper configuration of this plugin.
+ *   - ActivityPub plugin not installed and activated
+ *   - No supported Event Plugin installed and activated
  *
  * @since 1.0.0
  */
 class General_Admin_Notices {
 	/**
-	 * Warning if the plugin is Active and the ActivityPub plugin is not.
+	 * URL of the ActivityPub plugin. Needed when the ActivityPub plugin is not installed.
 	 */
-	public static function do_admin_notice_activitypub_plugin_not_enabled() {
-		$activitypub_plugin_url = 'https://wordpress.org/plugins/activitypub/';
+	const ACTIVITYPUB_PLUGIN_URL = 'https://wordpress.org/plugins/activitypub';
 
-		$notice = sprintf(
+	const ACTIVITYPUB_EVENT_EXTENSIONS_SUPPORTED_EVENT_PLUGINS_URL = 'https://code.event-federation.eu/Event-Federation/wordpress-activitypub-event-extensions#events-plugin-that-will-be-supported-at-first';
+
+	/**
+	 * Allowed HTML for admin notices.
+	 *
+	 * @var array
+	 */
+	const ALLOWED_HTML = array(
+		'a' => array(
+			'href'  => true,
+			'title' => true,
+		),
+		'br',
+		'i',
+	);
+
+	/**
+	 * Admin notice when the ActivityPub plugin is not enabled.
+	 *
+	 * @return string
+	 */
+	public static function get_admin_notice_activitypub_plugin_not_enabled(): string {
+		return sprintf(
 			/* translators: 1: the name of the event plugin a admin notice is shown. 2: The name of the ActivityPub plugin. */
 			_x(
 				'For the ActivityPub Event Extensions to work, you will need to install and activate the <a href="%1$s">ActivityPub</a> plugin.',
 				'admin notice',
 				'activitypub-event-extensions'
 			),
-			esc_html( $activitypub_plugin_url ),
+			esc_html( self::ACTIVITYPUB_PLUGIN_URL ),
 			admin_url( 'options-general.php?page=activitypub&tab=settings' )
 		);
-		$allowed_html = array(
-			'a' => array(
-				'href'  => true,
-				'title' => true,
-			),
-		);
-		echo '<div class="notice notice-warning"><p>' . \wp_kses( $notice, $allowed_html ) . '</p></div>';
 	}
 
 	/**
 	 * Warning that no supported event plugin can be found.
+	 *
+	 * @return string
 	 */
-	public static function do_admin_notice_no_supported_event_plugin_active() {
-		$supported_event_plugins_url = 'https://code.event-federation.eu/Event-Federation/wordpress-activitypub-event-extensions#events-plugin-that-will-be-supported-at-first';
-
-		$notice = sprintf(
+	public static function get_admin_notice_no_supported_event_plugin_active(): string {
+		return sprintf(
 			/* translators: 1: the name of the event plugin a admin notice is shown. 2: The name of the ActivityPub plugin. */
 			_x(
 				'The Plugin <i>ActivityPub Event Extensions</i> is of no use, because you do not have installed and activated a supported Event Plugin.
@@ -57,17 +73,28 @@ class General_Admin_Notices {
 				'admin notice',
 				'activitypub-event-extensions'
 			),
-			esc_html( $supported_event_plugins_url ),
+			esc_html( self::ACTIVITYPUB_EVENT_EXTENSIONS_SUPPORTED_EVENT_PLUGINS_URL ),
 			admin_url( 'options-general.php?page=activitypub&tab=settings' )
 		);
-		$allowed_html = array(
-			'a' => array(
-				'href'  => true,
-				'title' => true,
-			),
-			'br',
-			'i',
-		);
-		echo '<div class="notice notice-warning"><p>' . \wp_kses( $notice, $allowed_html ) . '</p></div>';
+	}
+
+	/**
+	 * Warning if the plugin is Active and the ActivityPub plugin is not.
+	 *
+	 * @return void
+	 */
+	public static function activitypub_plugin_not_enabled() {
+		$notice = self::get_admin_notice_activitypub_plugin_not_enabled();
+		echo '<div class="notice notice-warning"><p>' . \wp_kses( $notice, self::ALLOWED_HTML ) . '</p></div>';
+	}
+
+	/**
+	 * Warning when no supported Even Plugin is installed and active.
+	 *
+	 * @return void
+	 */
+	public static function no_supported_event_plugin_active() {
+		$notice = self::get_admin_notice_no_supported_event_plugin_active();
+		echo '<div class="notice notice-warning"><p>' . \wp_kses( $notice, self::ALLOWED_HTML ) . '</p></div>';
 	}
 }
diff --git a/includes/class-setup.php b/includes/class-setup.php
index 8ce20b6..cf2f799 100644
--- a/includes/class-setup.php
+++ b/includes/class-setup.php
@@ -11,8 +11,9 @@
 
 namespace Activitypub_Event_Extensions;
 
-use Activitypub_Event_Extensions\Admin\General_Admin_Notices;
 use Activitypub_Event_Extensions\Admin\Event_Plugin_Admin_Notices;
+use Activitypub_Event_Extensions\Admin\General_Admin_Notices;
+
 
 // Exit if accessed directly.
 defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
@@ -144,17 +145,21 @@ class Setup {
 	}
 
 	/**
-	 * Fires the initialization of admin notices for all active supported event plugins.s
+	 * Fires the initialization of admin notices.
 	 */
 	public function do_admin_notices(): void {
 		foreach ( $this->active_event_plugins as $event_plugin ) {
 			new Event_Plugin_Admin_Notices( $event_plugin );
 		}
+		// Check if any general admin notices are needed and add actions to insert the needed admin notices.
+
 		if ( ! $this->activitypub_plugin_is_active ) {
-			add_action( 'admin_notices', array( new General_Admin_Notices(), 'do_admin_notice_activitypub_plugin_not_enabled' ), 10, 1 );
+			// The ActivityPub plugin is not active.
+			add_action( 'admin_notices', array( 'Activitypub_Event_Extensions\Admin\General_Admin_Notices', 'activitypub_plugin_not_enabled' ), 10, 1 );
 		}
 		if ( empty( $this->active_event_plugins ) ) {
-			add_action( 'admin_notices', array( new General_Admin_Notices(), 'do_admin_notice_no_supported_event_plugin_active' ), 10, 1 );
+			// No supported Event Plugin is active.
+			add_action( 'admin_notices', array( 'Activitypub_Event_Extensions\Admin\General_Admin_Notices', 'no_supported_event_plugin_active' ), 10, 1 );
 		}
 	}
 
@@ -198,29 +203,24 @@ class Setup {
 		// Don't allow plugin activation, when the ActivityPub plugin is not activated yet.
 		if ( ! $this->activitypub_plugin_is_active ) {
 			deactivate_plugins( plugin_basename( ACTIVITYPUB_EVENT_EXTENSIONS_PLUGIN_FILE ) );
-			$notice = sprintf(
-				/* translators: 1: the name of the event plugin a admin notice is shown. 2: The name of the ActivityPub plugin. */
-				_x(
-					'To use this plugin install and activate the <a href="%1$s">%2$s</a> plugin first.',
-					'admin notice',
-					'activitypub-event-extensions'
-				),
-				esc_html( 'https://wordpress.org/plugins/activitypub' ),
-				esc_html( 'ActivityPub' )
-			);
-			$allowed_html = array(
-				'a' => array(
-					'href'  => true,
-					'title' => true,
-				),
-			);
+			$notice = General_Admin_Notices::get_admin_notice_activitypub_plugin_not_enabled();
 			wp_die(
-				wp_kses( $notice, $allowed_html ),
+				wp_kses( $notice, General_Admin_Notices::ALLOWED_HTML ),
 				'Plugin dependency check',
 				array( 'back_link' => true ),
 			);
 		}
-		// If someone installs this plugin, we simply enable ActivityPub support for the event post type, without asking.
+
+		if ( empty( $this->active_event_plugins ) ) {
+			deactivate_plugins( plugin_basename( ACTIVITYPUB_EVENT_EXTENSIONS_PLUGIN_FILE ) );
+			$notice = General_Admin_Notices::get_admin_notice_no_supported_event_plugin_active();
+			wp_die(
+				wp_kses( $notice, General_Admin_Notices::ALLOWED_HTML ),
+				'Plugin dependency check',
+				array( 'back_link' => true ),
+			);
+		}
+		// If someone installs this plugin, we simply enable ActivityPub support for all currently active event post types.
 		$activitypub_supported_post_types = get_option( 'activitypub_support_post_types', array() );
 		foreach ( $this->active_event_plugins as $event_plugin ) {
 			if ( ! in_array( $event_plugin['post_type'], $activitypub_supported_post_types, true ) ) {