diff --git a/src/transformer/events/core/course_viewed.php b/src/transformer/events/core/course_viewed.php
index 51ecd1494..644be281c 100644
--- a/src/transformer/events/core/course_viewed.php
+++ b/src/transformer/events/core/course_viewed.php
@@ -21,8 +21,16 @@
 use src\transformer\utils as utils;
 
 function course_viewed(array $config, \stdClass $event) {
+    global $CFG;
+
     $repo = $config['repo'];
-    $user = $repo->read_record_by_id('user', $event->userid);
+
+    // Get the userid or a valid userid for guest.
+    if (!isset($event->userid)) {
+        $event->userid = 0;
+    }
+    $userid = $event->userid == 0 && isset($CFG->siteguest) ? $CFG->siteguest : $event->userid;
+    $user = $repo->read_record_by_id('user', $userid);
     $course = $repo->read_record_by_id('course', $event->courseid);
     $lang = utils\get_course_lang($course);
 
diff --git a/src/transformer/events/core/user_created.php b/src/transformer/events/core/user_created.php
index 611fcb020..a3e26a80c 100644
--- a/src/transformer/events/core/user_created.php
+++ b/src/transformer/events/core/user_created.php
@@ -21,8 +21,17 @@
 use src\transformer\utils as utils;
 
 function user_created(array $config, \stdClass $event) {
+    global $CFG;
+
     $repo = $config['repo'];
-    $user = $repo->read_record_by_id('user', $event->relateduserid);
+
+    // Get the relateduserid or a valid relateduserid from the guest userid.
+    if (!isset($event->relateduserid)) {
+        $event->relateduserid = 0;
+    }
+    $relateduserid = $event->relateduserid == 0 && isset($CFG->siteguest) ? $CFG->siteguest : $event->relateduserid;
+    $user = $repo->read_record_by_id('user', $relateduserid);
+
     $lang = $config['source_lang'];
 
     return [[