I had a Dual BIOS/UEFI PC with Windows 10 and Debian 8 installed and working perfectly. I'm trying to install Ubuntu 20 on the Debian 8 partition. When 'Installation type', Windows was not shown at the options, so I chose Something else. At the partition selection, I chose Debian partition as /. When starting the installation I got the message:
No EFI System Partition was found. This system will likely not be able to boot successfully, and the installation process may fail. Please go back and add an EFI System Partition, or continue at your own risk.
So, I added an EFI partition of 1024Mb but then, the installation starts but after some time it says something like 'It failed trying to mount a vfat filesystem at /boot/efi.
How could I solve this?
Thanks