When there are active sessions on the targets discovered by an iSCSI discovery sendtarget address, you see these symptoms:
Cannot remove discovery address as there are active sessions on the targets discovered by this address.
ESXi prevents the removal of a discovery address if active TCP sessions exist between the host and the storage target. Additionally, when migrating an iSCSI VMkernel adapter to a DVS set for MTU 9000, the adapter may retain its original MTU 1500 setting, causing a mismatch that prevents session teardown.
To resolve this issue, manually terminate the active sessions before removing the discovery address.
esxcli iscsi session list esxcli iscsi session remove --name=<target_name> --adapter=<adapter_name>esxcli iscsi adapter discovery sendtarget remove --adapter=<adapter_name> --address=<IP_address:port> --force
For GUI method.
Please ensure that the following steps have been taken to unmount and detach any datastores. - Detach a LUN device from ESXi hosts
Note :
Target Removal: When removing a static iSCSI target that was populated via dynamic discovery, you must remove the dynamic target before performing a storage rescan. If you do not remove the dynamic target first, the host will automatically rediscover it and re-add it to the list of static targets during the rescan.
MTU Configuration: Ensure that Jumbo Frames (MTU 9000) are consistently configured end-to-end across the entire storage data path. This includes the vSwitch/DVS, physical network switches, and the storage array.
Host -> Configure -> Storage Adapters -> vmhba -> Static Discovery.
Select the iSCSI targets then click "remove"
If the target was discovered using Dynamic Discovery then switch to the Dynamic Discovery tab.
Select the Dynamic Discovery target and click remove.
Now since the static target has been removed and the session have been closed and the dynamic target has been removed, now you can rescan the adapter to update the changes.
For additional information:
How to remove iSCSI targets on ESXi
Host Profile Remediation Fails with iSCSI Session Errors
To speak with a customer representative or a Support Engineer see