ESXi 5 Hypervisor fatal boot error

For over 2 years now I've been running ESXi 5 just fine from a pen drive. I recently had to move the server to a new location and started seeing an issue.

Once the system starts to boot, I get:

'Error Loading /s.v00

Fatal error: 6 (Buffer too small)'

I'm not quite sure what could be happening. Nothing has changed. The only thing that was different is that the system was off and unplugged for 2 days.

In my google searches a few other started to see this issue after a power failure. The rig is connected to a UPS and I made sure to cleanly shutdown all guests and then the host itself.

What can I do here?

USB drives can fail. This is caused by either a corrupted file or bad media and can occur at random.

My general advice is to only boot ESXi from USB or SDHC card if you have SAN/NAS-based storage for your guests and are operating in a cluster. Otherwise, this can happen and cause unnecessary and frustrating downtime.

Please see: What happens when the USB key or SD card I've installed VMware ESXi on fails?

Also, this may be repairable, but likely isn't worth the effort. You may just have to reinstall ESXi onto known-good media and reimport your disk-based datastores and virtual machines.