In case of zabbix_sender usage we have emulating active checks. But - in case, when ANYTHING is wrong (Hostname missmatching, item has not exists, wrong item type, etc... )

We haven't reicieve any additional information - what is wrong, just useless info like

su -s /bin/bash -c 'zabbix_sender -vv -c /etc/zabbix/zabbix_agentd.conf -i /tmp/zbx-ceph-discovery.MtrCFNJhVvp' zabbix
zabbix_sender [3998631]: DEBUG: answer [ {"response":"success","info":"processed: 0; failed: 3; total: 3; seconds spent: 0.000824"}]
info from server: "processed: 0; failed: 3; total: 3; seconds spent: 0.000824"
sent: 3; skipped: 0; total: 3

And we can't understand what is wrong?

It would be great if trapper processes will answering in more details for zabbix_sender requests