On my newer PC, I have a FAT32 USB stick for my Rescue Media; it works great on my newer system which uses UEFI.
My old laptop (uses Legacy BIOS) created a Rescue Media successfully on a FAT32 USB stick but gives error, "Missing Operating System", when trying to boot from that USB stick.  I tried both settings for the checkbox (Enable Multi-boot) and the error was the same.  The only way I could solve the problem was to format the USB stick as NTFS and then create the Rescue Media.  I have to create Rescue media for more PCs and laptops.  Is there a general rule for the following parameters:
1. Rescue Media (USB stick) is FAT32 or NTFS
2. Enable Multi-boot should be checked or unchecked
At the moment I only tested two devices which finally work.
A) Old laptop with Legacy BIOS (I formatted USB as NTFS and uncheched Multi-boot)
B) Newer PC with UEFI (USB stick came preformatted as FAT32 and I checked Multi-boot)

Checking Enable Multi-boot will require the Rescue Media to use FAT32. I have no issues booting PCs in that setup, and it’s strange that it’s the old PC giving problems here. Maybe try another completely reinitializing that flash drive using the Diskpart “clean” command? That’s more extensive than reformatting. Or perhaps just try another flash drive. That shouldn’t matter if the same flash drive worked as NTFS, but I once found a flash drive and laptop combo where the laptop would only boot from Partition 1 when the flash drive was GPT, but would happily boot from other partitions when it was set up as MBR.

+x

 

jphughan - 19 January 2023 4:15 AM

Checking Enable Multi-boot will require the Rescue Media to use FAT32. I have no issues booting PCs in that setup, and it’s strange that it’s the old PC giving problems here. Maybe try another completely reinitializing that flash drive using the Diskpart “clean” command? That’s more extensive than reformatting. Or perhaps just try another flash drive. That shouldn’t matter if the same flash drive worked as NTFS, but I once found a flash drive and laptop combo where the laptop would only boot from Partition 1 when the flash drive was GPT, but would happily boot from other partitions when it was set up as MBR.

Thank you for your quick answer.  I spent an hour this morning repeating steps I did yesterday. Some facts for context:
- I never used Diskpart "clean". 
- Yesterday, Macrium actually formatted my USB from NTFS to FAT32 for one scenario.
Today I formatted my 2nd USB stick to FAT32.  I built Rescue media using Enable Multi-boot checked.  It booted successfully.
I rebuilt the Rescue Media again with Enable Multi-boot unchecked.  It also booted successfully.
Summary of results using my old HP laptop which uses Legacy BIOS:
1.  Both NTFS (Enable Multi-boot unchecked) and FAT32 USB sticks could boot successfully.
2. I don't know what caused the error (Missing Operating System) yesterday.