Steps to reproduce:

1. Add any host with any template
2. Try to delete it

Result:

Unable to delete any host as it just gives the same error message (with different graph IDs).
Expected:

To delete the host.

Additional info:

We have been using Zabbix since version 5, since then we had a migration over to Postgres (from MySQL) with Zabbix 6. We mostly use the Linux and the provided Mikrotik templates but others also seem to trigger the issue.

 

If I go into the database and delete the IDs from graph_discovery then the web interface deletes the host successfully. For now I changed the schema to include the "CASCADE ON DELETE" part on that relationship (as it is not there by default).