diff --git a/include/event.php b/include/event.php
index 9172e3ecca..0b6eb1020f 100644
--- a/include/event.php
+++ b/include/event.php
@@ -241,8 +241,8 @@ function event_store($arr) {
 
 	$a = get_app();
 
-	$arr['created'] = (($arr['created'])     ? $arr['created']         : DateTimeFormat::utcNow());
-	$arr['edited']  = (($arr['edited'])      ? $arr['edited']          : DateTimeFormat::utcNow());
+	$arr['created'] = (($arr['created'])     ? DateTimeFormat::utc($arr['created']) : DateTimeFormat::utcNow());
+	$arr['edited']  = (($arr['edited'])      ? DateTimeFormat::utc($arr['edited'])  : DateTimeFormat::utcNow());
 	$arr['type']    = (($arr['type'])        ? $arr['type']            : 'event' );
 	$arr['cid']     = ((intval($arr['cid'])) ? intval($arr['cid'])     : 0);
 	$arr['uri']     = (x($arr, 'uri')        ? $arr['uri']             : item_new_uri($a->get_hostname(), $arr['uid']));
diff --git a/src/Protocol/PortableContact.php b/src/Protocol/PortableContact.php
index d10c4db320..2cadf574f9 100644
--- a/src/Protocol/PortableContact.php
+++ b/src/Protocol/PortableContact.php
@@ -945,6 +945,15 @@ class PortableContact
 			$register_policy = $gserver["register_policy"];
 			$registered_users = $gserver["registered-users"];
 
+			// See discussion under https://forum.friendi.ca/display/0b6b25a8135aabc37a5a0f5684081633
+			// It can happen that a zero date is in the database, but storing it again is forbidden.
+			if ($last_contact < NULL_DATE) {
+				$last_contact = NULL_DATE;
+			}
+			if ($last_failure < NULL_DATE) {
+				$last_failure = NULL_DATE;
+			}
+
 			if (!$force && !self::updateNeeded($gserver["created"], "", $last_failure, $last_contact)) {
 				logger("Use cached data for server ".$server_url, LOGGER_DEBUG);
 				return ($last_contact >= $last_failure);