Bug? - Exception: Cron line added didn't remain in crontab on final check

I get this Error (via mail) once a week, and can´t find the reason for it.
Has anybody an idea what this could be?

Subject: Cron [email protected] [ -x /var/lib/asterisk/bin/schedtc.php ] && /var/lib/asterisk/bin/schedtc.php
Exception: Cron line added didn’t remain in crontab on final check in file /var/www/html/admin/libraries/BMO/Cron.class.php on line 103
Stack trace:

  1. Exception->() /var/www/html/admin/libraries/BMO/Cron.class.php:103
  2. FreePBX\Cron->addLine() /var/www/html/admin/libraries/BMO/Cron.class.php:170
  3. FreePBX\Cron->add() /var/www/html/admin/modules/timeconditions/Timeconditions.class.php:159
  4. FreePBX\modules\Timeconditions->updateCron() /var/www/html/admin/modules/timeconditions/bin/schedtc.php:87

FreePBX 13.0.131

I am seeing the same thing here

The solution is crontabs is not installed.

yum install crontabs.

It was fixed someday by itself,
i tried now to install crontabs -> already installed

So i don´t know if that was the issue, but since i have no problems atm everything is fine :wink:

But thanks for your help!