A couple of days ago, upgraded to 5.0-rc11. I had to copy over the new syslinux.cfg file to get the 4GB option to show up on boot. I had boot problems so I ran the make_bootable.bat on my thumbdrive via my Windows computer. I then got my UnRaid server to boot - once.

 

Today, I powered down to add a couple of drives. Now, my UnRaid box won't boot. When I power on, they system runs through all of the BIOS business all the way up until I should see the UnRaid boot selection screen. At that time it tells me that I need to need a boot disk (I can't recall the exact message).  I've ran the make_bootable.bat as admin again several times with the hope that it would resolve the issue. It has not.

 

Any assistance would be greatly appreciated.

Maybe it is trying to boot one of the new HDD's and not the flash drive?

Yep, this points towards incorrect boot drive being selected, or a USB stick failure (but then you say you can write to the USB from Windows by the looks, so probably the former.)

 

You have the X9, so choose the option to select boot item from the BIOS screen and force it to boot from USB.. if this works, go fix your BIOS settings

That's exactly what it was. I thought that I had changed and saved it in the BIOS. Apparently I hadn't. I'm an idiot. Sorry to waste your time. Nonetheless, your quick help is greatly appreciated.