diff -urN ../roundcubemail-1.6.1.orig/program/actions/mail/attachment_upload.php ./program/actions/mail/attachment_upload.php
--- ../roundcubemail-1.6.1.orig/program/actions/mail/attachment_upload.php	2023-01-23 22:03:14.000000000 +0200
+++ ./program/actions/mail/attachment_upload.php	2023-04-15 16:01:26.386602000 +0300
@@ -65,7 +65,8 @@
 
                 if (
                     $host == $url['host']
-                    && $port == $url['port']
+//                    && $port == $url['port']
+                    && (isset($url['port']) && $port == $url['port'])
                     && $rcmail->get_user_name() == rawurldecode($url['user'])
                 ) {
                     $message = new rcube_message($params['_uid'], $params['_mbox']);
@@ -184,7 +185,7 @@
 
     public static function get_attachment()
     {
-        return self::$COMPOSE['attachments'][self::$file_id];
+        return isset(self::$COMPOSE['attachments'][self::$file_id]) ? self::$COMPOSE['attachments'][self::$file_id] : null;
     }
 
     public static function attachment_success($attachment, $uploadid)