Error on Front Page

Upcoming Events
FATAL ERROR: UNCAUGHT EXCEPTION: DATETIME::__CONSTRUCT(): FAILED TO PARSE TIME STRING (21/11/2018) AT POSITION 0 (2): UNEXPECTED CHARACTER IN /APP/PUBLIC/WP-CONTENT/THEMES/FICTIONAL UNIVERSITY/FRONT-PAGE.PHP:32 STACK TRACE: #0 /APP/PUBLIC/WP-CONTENT/THEMES/FICTIONAL UNIVERSITY/FRONT-PAGE.PHP(32): DATETIME->__CONSTRUCT('21/11/2018') #1 /APP/PUBLIC/WP-INCLUDES/TEMPLATE-LOADER.PHP(74): INCLUDE('/APP/PUBLIC/WP-...') #2 /APP/PUBLIC/WP-BLOG-HEADER.PHP(19): REQUIRE_ONCE('/APP/PUBLIC/WP-...') #3 /APP/PUBLIC/INDEX.PHP(17): REQUIRE('/APP/PUBLIC/WP-...') #4 {MAIN} THROWN IN /APP/PUBLIC/WP-CONTENT/THEMES/FICTIONAL UNIVERSITY/FRONT-PAGE.PHP ON LINE 32

cannot wrap my head around this one...
code:
 <?php $homepageEvents = new WP_Query(array(
              'posts_per_page' => 2,
              'post_type' => 'event'

        ));

        while($homepageEvents->have_posts()) {
          $homepageEvents->the_post(); ?>

       <div class="event-summary">
          <a href="#">
            <span class="event-summary__month"><?php 
             $eventDate = new DateTime(get_field('event_date'));
              echo $eventDate->format('M')
             ?></span>
            <span class="event-summary__day"><?php echo $eventDate->

• This topic was modified 7 years, 3 months ago by Jan Dembowski.
• This topic was modified 7 years, 3 months ago by Jan Dembowski.