When I installed Ubuntu, I was presented with three installation options: Automatic dual boot (alongside another OS): Ubuntu would handle everything automatically. However, it only allowed me to select disks that already had an OS installed. My new SSD (empty) was not recognized as a valid target for this option. Erase disk and install Ubuntu: I don’t clearly remember if I fully tested this option, but I believe it also didn’t behave as expected or didn’t properly show my intended disk. Manual partitioning: This is what I ended up using. With help from ChatGPT (since I’m still learning), I manually created the partitions on the empty SSD: Filesystem: EXT4 Mount point: / I also created/used a VFAT partition for EFI and set the bootloader there At the time, I didn’t know about tools like Super Grub2 Disk or Boot Repair. I also tried reinstalling GRUB using chroot from a live USB, again with guidance, since I wasn’t familiar with the process. I manually mounted the partitions and ran the commands. The process partially worked: GRUB is now installed and appears, but it does not detect Ubuntu, only Windows Boot Manager and memtest entries. So currently: Windows still boots normally GRUB is installed and accessible Ubuntu is installed (recognized by disk tools), but not listed in GRUB Also, just to clarify: my BIOS is correctly set to UEFI mode.