Here is the KB Article describing the problem;
https://kb.vmware.com/s/article/84249
You need to copy boot.cfg from bootbank to /altbootbank and edit it.
SSh to the ESXi host in question.
- cp /bootbank/boot.cfg /altbootbank/boot.cfg
- vi /altbootbank/boot.cfg
Change the first line 'bootstate=0' > 'bootstate=3'
Change last line 'updated=N' > 'update=N-1' (eg update=3 > updated=2)
- Save file
Reboot and test it.