This question already has an answer here:
I'm seeing tons of similar questions but never this scenario, or at least not with a solution...
I have an Acer Aspire laptop, no optical drive, with Windows 10 installed. BIOS is set to Legacy boot, and Windows works perfectly.
I downloaded Ubuntu 15.10 x64 and put it on a USB stick after using DISKPART to prepare the drive. I want to dual-boot Windows and Ubuntu.
When I boot from USB in Legacy, I get "Operating System Not Found". I've tried changing USB ports and drives, using both FAT32 and NTFS when formatting, never makes a difference.
I change BIOS to use UEFI instead of Legacy, and the USB drive boots perfectly and starts installation. In the installation process, it tells me that installing Ubuntu in UEFI will hose my other operating system. I think it'll let me do a full wipe of the hard disk and install, but I want to keep my Windows partition.
I'm assuming that if I can just get the USB drive to boot in Legacy mode, everything will be fine, but I can't figure out how to do that. Otherwise, if I could change my Windows partition so that it's UEFI instead of Legacy, I assume that would work too.
Any way you can think of to do either of these, or any other solution?
I wouldn't consider it a duplicate of the other question because I'm hoping to stay in Legacy mode so I can keep my Windows installation - that question is for a UEFI installation.