Hello, i wanted to use one of my hard drives to play around with the latest manjaro kde as a dual boot next to my already existing Win 10. Now i made a bootable usb drive and all, but when im trying to install it it wont boot from the usb stick and tells me somthing about a grub error. What did i do wrong here? Win 10 is just working fine.
which iso are you using ?
date and version please
How did you prepare the USB stick? Recommendable is Etcher. Check the checksum after burning.
Also, Windows need to be shutdown, not staying in any type of hibernate mode, switch off Fastboot in Windows and Secure boot in firmware.
I used the lastest version available from the manjaro website “manjaro-kde-20.0.3-200606-linux56.iso”
use ventoy for initialize USB
https://osdn.net/projects/manjaro/storage/kde/20.1-rc4/manjaro-kde-20.1-rc4-200816-linux58.iso
https://osdn.net/projects/manjaro/storage/kde/20.1-rc4/manjaro-kde-20.1-rc4-200816-linux58.iso.sig
Thank you all very much all your anwsers combined worked for me, ist started booting from the usb stick to install manjaro. Sadly i ran into the next problem.
I also tried installing it and worked, but when i boot the installed manjaro it looks like this -> 15978425144502091312302245142410|666x500
ok now, i know what caused these errors. it was my second graphics card, when it is disabled manjaro now works just fine. so i would say thread ist closed
please give us more info’s 
Start a live-usb-session an give us output from terminal:
inxi -Fxxxzra --no-host
in the live-usb-session you can chroot-manjaro with: (install Manjaro repair/mount over live-session)
sudo manjaro-chroot -a
example in the first post / picture