Symptom

Unable to delete the switch in NDFC due to Failed to remove the switch [...] Cannot invoke "java.net.InetAddress.getHostAddress()" because "ip" is null

Conditions

After performing a write erase and reload on multiple devices, the discovery status of the device that cannot be deleted becomes not ok, displaying as Unreachable or showing an "Unknown User or Password" status.

Workaround

Ensure that the problematic device is reachable and that SNMP is functioning properly. Then, trigger a rediscovery from the GUI. Once the switch discovery status returns to ok, you can proceed with deletion.

Further Problem Description