Customer node1 display "Waiting for giveback...(Press Ctrl-C to abort wait)" and "Entering FM state:5 because mbFound:0 local in headswap:0", node2 storage failover show display "Kernel loaded".
The node1 display "Waiting for giveback", could node2 execute giveback to node1?
Refer KB https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Systems/FAS_Systems/Entering_FM_state%3A5_on_AFF-A400_during_ONTAP_upgrade Solution reboot the node, is reboot problem node1 or alive node2?
See The Solution
Reboot the offline node. I have updated the KB to fix the confusion. Also bug link was broken so I fixed it.
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Thanks for your update. BTW, customer model is FAS2720 and problem occurred not in upgrade OnTap. But the error same as the KB.
After reboot offline few times still cannot fix the problem, we will contact NetApp support.