Error when creating a new Customer/User/Domain

  • Since a few days i have following issue: if i create a new User/Customer in any of my Reselleraccounts a exception is thrown:

    There where no updates or anything else. All other features are working fine.

    How should i fix this issue?

    My System is Debian 9 with i-MSCP 1.5.3 Build: 2018120800