From 86bb99e45e8ec1b27bce3a5c3a5892d43ab91c11 Mon Sep 17 00:00:00 2001
From: Ralf Becker <RalfBecker@outdoor-training.de>
Date: Fri, 5 Jun 2020 11:17:37 +0200
Subject: [PATCH] * Calendar/CalDAV: videoconference was lost, if meeting was
 accepted of updated via CalDAV

---
 calendar/inc/class.calendar_ical.inc.php | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/calendar/inc/class.calendar_ical.inc.php b/calendar/inc/class.calendar_ical.inc.php
index a7a2ec1782..878db63d41 100644
--- a/calendar/inc/class.calendar_ical.inc.php
+++ b/calendar/inc/class.calendar_ical.inc.php
@@ -1308,12 +1308,13 @@ class calendar_ical extends calendar_boupdate
 						}
 					}
 				}
-				// unset old X-* attributes stored in custom-fields
+				// unset old X-* attributes stored in custom-fields with exception of our videoconference and notify-externals
 				foreach ($event_info['stored_event'] as $key => $value)
 				{
 					if ($key[0] == '#' && $key[1] == '#' && !isset($event[$key]))
 					{
-						$event[$key] = '';
+						$event[$key] = in_array($key, ['##videoconference', '##notify_externals']) ?
+							$value : '';
 					}
 				}
 				if ($merge)