I had this long blog post I was going to write about HP screwing me on a ESXi upgrade, but in a nut shell you can read these ones about that how shebang:
As both of them mention you have to do a clean install, and you probably won’t have a config saved from that exact version as you are just updating to it, so your config on the old 5.x or 6.0 won’t work either. If you have dvswitches and all that fun jazz probably not a huge deal but if you have standard vswitches and lots of custom configurations around them including vlan tagging, well this can be crappy.
I did manage through all my trial n errors to get a working copy but it required workarounds I don’t think would have been supported, so meh just follow those…
I tried everything to get a ESXi system upgraded to 6.7 without loosing or reconfiguring the host, you figure just do anew install and reload the config.
However you can only load config for the same version a backup of that one was created. I eventually came across other things other PSOD’s and had to even at one point edit the boot file to remove a HP dedicated driver from loading. After all that meh, just install new with the custom images mentioned in the above Blogs.
I’m really sorry I would have covered these tasks in far more detail but spent a good couple days smashing my head just trying to get it to work. something are just not worth the effort, and blogging every annoying error and steps along the way on this one… is just one of those things.