Error: A general system error occurred: Error Stack Call “IscsiManager.QueryCandidateNics” for object “iscsiManager” on ESXi “<Your Host Here>” failed
You may run into this error on VMWare ESXi hosts when trying to modify the network interfaces used for iSCSI.
I normally see it happen when someone messed up or entirely removed the NICs that were in use for iSCSI without first removing them from the iSCSI bindings.
The only way I’ve found to get rid of this error is to connect to the host using the application client (web client gives a “general error” and doesn’t allow you to do anything). You can still connect directly to a host in vSphere 6.5 using the 6.0 client. You will need to first disable and remove the iSCSI software adapter, and then remove the iSCSI configuration files and reboot.
Needless to say, shut down or migrate all VMs and make sure there is no disk I/O activity towards iSCSI on the host.
You will navigate to the host configuration and go into the properties of the iSCSI software adapter.
Open the configure window, and if required, copy the IQN from the name field into a text file if you want to use the same name. When you recreate a new software adapter, you can copy paste the old name back into here.
After un-checking and closing the configuration windows, VMWare will warn you to reboot. To avoid wasting time, do not reboot yet and proceed to the next step.
Deleting the iSCSI Configuration from the System
If you simply disable the adapter, reboot and add a new adapter, it will immediately obtain the old problematic settings from files stored on the host and you will be back to square one.
To delete the configuration files, connect either in SSH or SFTP and navigate to the following directory:
It’s a good idea to make a backup copy of the contents of the directory, then delete the contents and reboot the ESXi host.
After rebooting you can add a new, clean software adapter. If required you can copy/paste the IQN you saved previously.