решение:

Закомментировать строку 103 в /var/www/html/admin/libraries/BMO/Cron.class.php

                        // It didn't stick. WTF? Put our original one back.
                        $this->installCrontab($backup);
//                      throw new \Exception("Cron line added didn't remain in crontab on final check");
                } else {
                        // It was already there.