Hey everyone , i recently heard about CachyOS , so i decide to install it on a old laptop. (Vaio don’t got the exact model would edit the message after that)
I formatted the USB , put cachyos , launch it on my computer. i launched the installation with GNOME And Limine if i’m not wrong …
and after a few moments i got an error message , here the copy : b81b850
Thanks in advance have a wonderful day
So a part of your log says:
error: The partition selected to install the BIOS boot code to contains
a recognised filesystem.
Pass `--force` to override these checks.
**ONLY DO THIS AT YOUR OWN RISK, DATA LOSS MAY OCCUR!**
Looks like it failed because of some existing file system. Don’t know why the installer didn’t detect it when setting up partitions during install configuration. If you don’t have any important data in your laptop (since you said it’s an old one) you may try to format the whole hard drive. There should be a option called replace a partition in the installer. Or do it manually using tools included in CachyOS live (should be KDE partition manager but I don’t know exactly how to use it since I personally do it in a different way by using a WinPE installed in my usb drive. You may search google for how to use KDE partition manager)
Im a bit late , but im know back on this computer for working on it , i really appreciated your message , cause it confirm my doubt, as i said im still a noob into those things.
I downloaded Gparted for wiping my Hard Drive , but i get trouble to launch it correctly , so i will try to launch again CachyOS , and do what you told me , as again reall appreciate the help !
So i tried your method , i finally manage to partition aall the HardDrive , but now i got this 
i try to install Limine actually , i manually make my 2 partition as sayed in the wiki :
Any ideas ?
Edit : Now in KDE i got my main drive on /dev/sda
i got an Unknown type of partition with mount point /run
and the rest as a free space
Edit 2 : i’m actually shred everything and see after that
Edit 1: I searched in your install log and found the installer actually tried to change your partition table into MBR but failed so it’s not the cause. The answer below "="s may be misleading. You may try to change the partition table yourself and try again. The Jan topic mentioned using fdisk (or gdisk) to convert your drive into MBR. I found multiple advices suggesting defferent ways, hard to tell which of them are correct. Will edit again when I confirm. You can also try to google yourself during that.
Edit 2: Found a Arch Wiki using sgdisk. Could be helpful:
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This time I couldn’t find any useful information by myself so I asked AI for you. So the thing is your laptop seems to be booting in Legacy mode instead of UEFI while your hard drive is in GPT format instead of MBR (which is required if you are booting in Legacy mode). I searched google and found a topic back in Jan with similar issue:
So it seems to be a bug of cachyos installer as it formats your drive into GPT whichever boot mode your pc is in. You may follow this guy’s suggestion and download an older installer of CachyOS. Don’t worry about older software stuff as Arch Linux which Cachy bases on is a rolling update OS so simply run a pacman update command and your system will be up to date. For your installer USB if you don’t mind I strongly suggest you to use ventoy
since it enables you to store and boot from any one of multiple .iso files instead of only one, which is helpful since you are having 2 installers involved in your situation.
AI also suggests you to check BIOS of your laptop to see if there are any options to switch your boot type to UEFI. But it says your laptop may be too old and probably only supports Legacy so using an older installer seems to be the quickest way to solve your problem.