Reload failed because retrieve_conf encountered an error: 255

Upgrade from 12 to 13, following error -

exit: 255
sh: /usr/bin/crontab: No such file or directory
Unable to continue. Cron line added didn't remain in crontab on final check in /var/www/html/admin/libraries/BMO/Cron.class.php on line 113
#0 /var/www/html/admin/libraries/BMO/Cron.class.php(180): FreePBX\Cron->addLine('* * * * * [ -x ...')
#1 /var/www/html/admin/modules/timeconditions/Timeconditions.class.php(159): FreePBX\Cron->add('* * * * * [ -x ...')
#2 /var/www/html/admin/modules/timeconditions/functions.inc.php(198): FreePBX\modules\Timeconditions->updateCron()
#3 /var/www/html/admin/libraries/BMO/DialplanHooks.class.php(95): timeconditions_get_config('asterisk')
#4 /var/lib/asterisk/bin/retrieve_conf(866): FreePBX\DialplanHooks->processHooks('asterisk', Array)
#5 {main}

You need to install cron tab

[re] installing cron tab solved the problem, thank you.