Looks like the email notification setup for expiring contracts is not working as expected. I'd suggest verifying the SMTP settings, notification group, and testing the system directly to troubleshoot the issue.
Hi @Oya-Erdayı
did your purge the objects completely?
It looks like that you have still archived or deleted objects created for the object type.
If you have still archived, deleted or maybe unfinished objects you can purge them in the system administration of i-doit:
Administration → Systemtools → Cache / Database → Objects or Categories