I've been trying to dual boot Windows 10 and Ubuntu 18.04. I know my Windows 10 is in Legacy mode. For some reason, Ubuntu decided to install in UEFI mode, which caused me a lot of problems when trying to dual boot (aka unable to do so).
I want to reinstall Ubuntu in Legacy mode. Whenever I boot into the installer (now that I have Ubuntu installed and want to reinstall it), for some reason it tries to mount my drives (it really shouldn't). This of course fails and bumps me to the initramfs prompt.
I cannot simply remove the drive since that's where I want to install Ubuntu, but I don't even get that far. The installer is trying to mount /dev/sdc2 to /cow, but that is entirely unrelated to the install process. Same thing happens when trying to go into Live Ubuntu instead.
Edit: As it turns out, a persistent partition was created on my USB live installer. It was trying to load this and failing. Removing the persistent storage solved the issue. Additionally, when booting in UEFI mode, my USB drive is /dev/sdd, and when booting in Legacy mode, it is /dev/sdc, hence the confusion.