diff --git a/projects/plugins/jetpack/_inc/lib/icalendar-reader.php b/projects/plugins/jetpack/_inc/lib/icalendar-reader.php
index 572b85c45cb3e..11b728c3a4545 100644
--- a/projects/plugins/jetpack/_inc/lib/icalendar-reader.php
+++ b/projects/plugins/jetpack/_inc/lib/icalendar-reader.php
@@ -147,13 +147,13 @@ public function apply_timezone_offset( $events ) {
 				$start_time = preg_replace( '/Z$/', '', $event['DTSTART'] );
 				$start_time = new DateTime( $start_time, $this->timezone );
 				$start_time->setTimeZone( $timezone );
-
-				$end_time = preg_replace( '/Z$/', '', $event['DTEND'] );
-				$end_time = new DateTime( $end_time, $this->timezone );
-				$end_time->setTimeZone( $timezone );
-
 				$event['DTSTART'] = $start_time->format( 'YmdHis\Z' );
-				$event['DTEND']   = $end_time->format( 'YmdHis\Z' );
+				if ( isset( $event['DTEND'] ) ) {
+					$end_time = preg_replace( '/Z$/', '', $event['DTEND'] );
+					$end_time = new DateTime( $end_time, $this->timezone );
+					$end_time->setTimeZone( $timezone );
+					$event['DTEND'] = $end_time->format( 'YmdHis\Z' );
+				}
 			}
 
 			$offsetted_events[] = $event;
@@ -231,9 +231,9 @@ protected function filter_past_and_recurring_events( $events ) {
 
 			// Process events with RRULE before other events.
 			$rrule = isset( $event['RRULE'] ) ? $event['RRULE'] : false;
-			$uid   = $event['UID'];
+			$uid   = isset( $event['UID'] ) ? $event['UID'] : false;
 
-			if ( $rrule && ! in_array( $uid, $set_recurring_events, true ) ) {
+			if ( $rrule && $uid && ! in_array( $uid, $set_recurring_events, true ) ) {
 
 				// Break down the RRULE into digestible chunks.
 				$rrule_array = array();
diff --git a/projects/plugins/jetpack/changelog/fix-icalendar-reader-warnings b/projects/plugins/jetpack/changelog/fix-icalendar-reader-warnings
new file mode 100644
index 0000000000000..137eb927f0deb
--- /dev/null
+++ b/projects/plugins/jetpack/changelog/fix-icalendar-reader-warnings
@@ -0,0 +1,5 @@
+Significance: patch
+Type: other
+Comment: Jetpack iCalendarReader: Fix Undefined array key Warnings
+
+