So i tried installing elementary on my friend's computer

I keep ending up with this error : 'in it ram fs : cannot find a medium with a live file system'

This error can be replicated on one other computer but works without the error on another one.

I'm using a UEFI boot on all of them
What I've tried :
1. Switching USB ports
2. Burning the image using Rufus, lily USB
3.secure boot on/off
4. Converted any dynamic partitions to basic
5. Converted MBR to GPT
6. Disabled Intel PTT

I've tried Ubuntu as well, same results

If you use UEFI disable CSM & Secure Boot in your BIOS, this way you make sure you boot in UEFI mode.
Also check if your USB contains /EFI/boot/bootx64.efi in it.

Some ISO to USB writing tools tend to install their own bootloader without EFI mode, so you may want to search for a tool copying your iso to USB as a whole.
Best option is to use the linux command "dd".
There should be a manual for USB setup.

@Haxk20 why?
Most linux are EFI compatible. I installed it many times with EFI only boot...

@qbasic16 Is efi bios or? (not my field really)

Did you verify the downloaded image wasn't corrupted?

@Haxk20 legacy is very slow. If he can boot the USB with UEFI only, he should use UEFI. Legacy has the problem tjat the MBR could be overwritten by different stuff, it is not the way to go anymore if your hardware supports EFI boot.

@Haxk20 bootx64.efi is in every single linux ISO i have seen the recent years. (64bit only)
On 32bit it is named bootia32.efi.

@linuxxx
BIOS is the tiny code controlling your mainboard, there you can set boot order and other stuff.

EFI is a newer kind of booting.
There is the old MBR booting (legacy) and the newer and recommended (U)EFI.
EFI doesn't use a MasterBootRecord anymore but it needs a specific file:
/efi/boot/bootx64.efi (64bit)
/efi/boot/bootia32.efi (32bit)

Mostly the OS (Win & Linux) creates during installation a separate "EFI" partition containing one of those files so the mainboard BIOS can find abd boot it.

@Haxk20 Yeah the CMOS chip

@TheAnimatrix
Try out what is written in my first comment.
Some Mainboard BIOS need you in order to boot from the USB stick to initialize it with GPT format and put the ISO content on an NTFS partition on the USB.

If you use EFI boot you can simply extract the whole ISO content to the USB. EFI does not need you to "burn" an ISO (this is only needed if you want your USB to be able to boot in legacy/MBR mode too!)

So EFI only needs a filestructure on the USB with the file
/efi/boot/bootx64.efi
(or bootia32.efi for 32bit)
No need for burning tools.

Change the software you used to write the image to the USB and download the ISO again. If you're on Windows, get the file hash with the 'Get-FileHash' cmdlet.

As i said:
If he has EFI boot support on the PC, (which nowadays all systems have) and if his ISO has an EFI boot loader (which nowadays all linux have)
then he only has to COPY the content of the ISO and paste it on a USB stick.
No need to install some "ISO burner" software. (ISO "burning" is ONLY needed, if you want MBR/legacy boot support for your USB)

Trust me, I was deep down the rabbit hole once. Tried all combinations of MBR, EFI and 32/64bit on USBs with GPT/MBR with NTFS/FAT/FAT32/ext3...
After all I was able to create an external HDD which contained installers for:
Win7, Win8, Win10,
Ubuntu, GParted, Kali
(all 32 & 64bit)

@Haxk20 tried legacy didn't work

@iguana Cross checked the hash

@qbasic16 so you want me to try extracting the files to the USB drive and also with the NTFS format? Also what is this 'dd' you recommend, you mean disk drive?

Also another problem, I installed elementary with the same USB on another computer, everything went smooth however there is no Grub, how do I boot into the OS.. I'm pretty sure I installed IN UEFI mode so grub won't exist right, so how do I boot into the OS?

dd is a commandline tool. Try
man dd

Don't you just need to set up a ram partition and map it with initramfs.

Also don't you mean "initramfs"?

@Numinex yeah I meant initramfs, was just the correction. How do I do what you just said and is that why I get the error cannot medium with live file system

@TheAnimatrix ist the initramfs error after the installation finished or when you boot from USB into the linux setup?

@qbasic16 on booting from the USB drive, I can't even get in the installation part

@TheAnimatrix

Firstly like @qbasic16 asked. Is this pre install or after you install?

Secondly, check with parted or something similar if you've got a partition that has the flag linux-swap on it. If you have it, then run initramfs /dev/sdXx. If you don't have it, then Google how much swap space you need with how much actual physical ram you've got. Then create a swap partiton and set the swap flag. After that do the same as before initramfs /dev/sdXx. Where X is what drive USB, hardrive or whatever, then that drive gets translates into a number (which you can check with lsblk) and the little x is the partition number which you can check with parted with typing a lowercase L.

Now if anything goes wrong or if I'm wrong (which may be possible, other ranters please correct me) then check the arch wiki which has some excellent instructions.

@Numinex pre install, can't even boot the preliminary live OS

@TheAnimatrix Oh, then my solution won't work, do some more research on the bios thing the others were talking about.

@TheAnimatrix maybe download it a 2nd time...
I don't know anything else atm. Maybe google helps..

@qbasic16 I'll try another thumb drive or maybe another OS..

@TheAnimatrix I may have just come up with a solution. If the other stuff on the computer like previous os doesn't matter then do a total wipe of the entire disk and reset the bios. Perhaps even look up other compatible bioses that might work and flash them. And when you've nuked the drive try booting the USB and do a clean install.

@Numinex what doesn't make sense is i got this error in a computer where I could successfully install kali Linux, also the same thumb drive did work in another computer, I successfully installed elementary on another laltop that is..

I can't blame it on any of them at the moment

@TheAnimatrix Yeah that sounds really strange. Did you verify the hashes?