I converted zabbix DB from mysql (MariaDB 5.5) to PostgreSQL with this toolhttps://github.com/philipsoutham/py-mysql2pgsql.
Now:
if i try to delete any Triggers i see the following error:

eleted: Trigger "HTTPCode_Backend_5XX on

" on "AWS ELB CloudWatch".
pg_query(): Query failed: ERROR: update or delete on table "triggers" violates foreign key constraint "functions_triggerid_fkey" on table "functions" DETAIL: Key (triggerid)=(14202) is still referenced from table "functions". [triggers.php:316 ? CAPIObject->delete() ? CAPIObject->__call() ? czbxrpc::call() ? czbxrpc::callAPI() ? call_user_func() ? CTrigger->delete() ? CTrigger->deleteByIds() ? CZBXAPI->deleteByIds() ? DB::delete() ? DBexecute() ? pg_query() in /usr/share/zabbix/include/db.inc.php:509]
Error in query [DELETE FROM triggers WHERE triggerid='14202'] [ERROR: update or delete on table "triggers" violates foreign key constraint "functions_triggerid_fkey" on table "functions" DETAIL: Key (triggerid)=(14202) is still referenced from table "functions".]
SQL statement execution has failed "DELETE FROM triggers WHERE triggerid='14202'"

and, if i try to delete any IT Services i see the following errors:

pg_query(): Query failed: ERROR: update or delete on table "services" violates foreign key constraint "service_alarms_serviceid_fkey" on table "service_alarms" DETAIL: Key (serviceid)=(2) is still referenced from table "service_alarms". [services.php:106 ? CAPIObject->delete() ? CAPIObject->__call() ? czbxrpc::call() ? czbxrpc::callAPI() ? call_user_func() ? CService->delete() ? DB::delete() ? DBexecute() ? pg_query() in /usr/share/zabbix/include/db.inc.php:509]
Error in query [DELETE FROM services WHERE serviceid='2'] [ERROR: update or delete on table "services" violates foreign key constraint "service_alarms_serviceid_fkey" on table "service_alarms" DETAIL: Key (serviceid)=(2) is still referenced from table "service_alarms".]
SQL statement execution has failed "DELETE FROM services WHERE serviceid='2'"