diff --git a/mod/cal.php b/mod/cal.php
index 1ac11dc98..2992f29e5 100644
--- a/mod/cal.php
+++ b/mod/cal.php
@@ -24,7 +24,6 @@
  */
 
 use Friendica\App;
-use Friendica\Content\Feature;
 use Friendica\Content\Nav;
 use Friendica\Content\Text\BBCode;
 use Friendica\Content\Widget;
@@ -69,7 +68,6 @@ function cal_init(App $a)
 	}
 
 	$a->profile = Profile::getByNickname($nick, $a->profile_uid);
-
 	if (empty($a->profile)) {
 		throw new HTTPException\NotFoundException(DI::l10n()->t('User not found.'));
 	}
@@ -131,6 +129,9 @@ function cal_content(App $a)
 	// Setup permissions structures
 	$owner_uid = intval($a->data['user']['uid']);
 	$nick = $a->data['user']['nickname'];
+	if (empty($a->profile)) {
+		throw new HTTPException\NotFoundException(DI::l10n()->t('User not found.'));
+	}
 
 	$contact_id = Session::getRemoteContactID($a->profile['uid']);
 
diff --git a/mod/events.php b/mod/events.php
index d4a902c72..bf813f683 100644
--- a/mod/events.php
+++ b/mod/events.php
@@ -30,6 +30,7 @@ use Friendica\Core\Theme;
 use Friendica\Core\Worker;
 use Friendica\Database\DBA;
 use Friendica\DI;
+use Friendica\Model\Contact;
 use Friendica\Model\Event;
 use Friendica\Model\Item;
 use Friendica\Model\User;
@@ -129,7 +130,7 @@ function events_post(App $a)
 	];
 
 	$action = ($event_id == '') ? 'new' : 'event/' . $event_id;
-	$onerror_path = 'events/' . $action . '?' . http_build_query($params, null, null, PHP_QUERY_RFC3986);
+	$onerror_path = 'events/' . $action . '?' . http_build_query($params, '', '&', PHP_QUERY_RFC3986);
 
 	if (strcmp($finish, $start) < 0 && !$nofinish) {
 		notice(DI::l10n()->t('Event can not end before it has started.'));
diff --git a/mod/message.php b/mod/message.php
index 7a8b133f5..f12f54015 100644
--- a/mod/message.php
+++ b/mod/message.php
@@ -332,7 +332,7 @@ function message_content(App $a)
 				'id' => $message['id'],
 				'from_name' => $from_name_e,
 				'from_url' => $from_url,
-				'from_addr' => $contact['addr'],
+				'from_addr' => $contact['addr'] ?? $from_url,
 				'sparkle' => $sparkle,
 				'from_photo' => $from_photo,
 				'subject' => $subject_e,
diff --git a/src/Model/Event.php b/src/Model/Event.php
index 5139abc43..db99ae571 100644
--- a/src/Model/Event.php
+++ b/src/Model/Event.php
@@ -291,6 +291,9 @@ class Event
 		}
 
 		$contact = DBA::selectFirst('contact', [], $conditions);
+		if (!DBA::isResult($contact)) {
+			Logger::warning('Contact not found', ['condition' => $conditions, 'callstack' => System::callstack(20)]);
+		}
 
 		// Existing event being modified.
 		if ($event['id']) {