Help! The rbd-target-api service of iSCSI gw cannot be started

Help! The rbd-target-api service of iSCSI gw cannot be started

Two servers form iSCSI GW,

[root@ceph-node1 ~]# systemctl reset-failed rbd-target-api.service
[root@ceph-node1 ~]# systemctl start rbd-target-api.service
[root@ceph-node1 ~]# gwcli
Unable to access the configuration object : REST API failure, code : 500
GatewayError:
[root@ceph-node1 ~]# systemctl status rbd-target-api
● rbd-target-api.service - Ceph iscsi target configuration API
Loaded: loaded (/usr/lib/systemd/system/rbd-target-api.service; enabled; vendor preset: disabled)
Active: failed (Result: start-limit) since Fri 2021-07-30 11:25:58 CST; 15min ago
Process: 11678 ExecStart=/usr/bin/rbd-target-api (code=exited, status=1/FAILURE)
Main PID: 11678 (code=exited, status=1/FAILURE)

Jul 30 11:25:58 ceph-node1 systemd[1]: Unit rbd-target-api.service entered failed state.
Jul 30 11:25:58 ceph-node1 systemd[1]: rbd-target-api.service failed.
Jul 30 11:25:58 ceph-node1 systemd[1]: rbd-target-api.service holdoff time over, scheduling restart.
Jul 30 11:25:58 ceph-node1 systemd[1]: Stopped Ceph iscsi target configuration API.
Jul 30 11:25:58 ceph-node1 systemd[1]: start request repeated too quickly for rbd-target-api.service
Jul 30 11:25:58 ceph-node1 systemd[1]: Failed to start Ceph iscsi target configuration API.
Jul 30 11:25:58 ceph-node1 systemd[1]: Unit rbd-target-api.service entered failed state.
Jul 30 11:25:58 ceph-node1 systemd[1]: rbd-target-api.service failed.
[root@ceph-node1 ~]#

This is where is the problem, how to troubleshoot this kind of need
Thank you very much for your answer

Start by reproducing the failure with systemctl for rbd-target-api.service and gwcli, then inspect the service's startup output and the REST API 500 error. The issue provides no source file or test entry point, so trace the service configuration and logs before deciding what is wrong. Done means the service starts reliably and gwcli can access the configuration object.

Written by the indexing model from the issue text.