How connect a usb source to OSMC with Raspberry Pi

Hi, i’m trying to connect a usb source to OSMC, i have OSM with a USB installation, and i have two usb port in my raspberry one with the usb drive to run osmc, and in the other i have a hd usb with some media file, i have connect the hd usb and then i have power on the raspberry, and this is the screen i get:

i have then shutdown the raspberry, how i can fix this problem, how i can use the hd usb to source for my media?

If you’re trying to connect it direct to the pi usb socket live, theen it’s not too surprising. Try with booting with the disc connected, or connect via a powered usb hub (when you may be able to connect live).
Derek

If you are using a USB install plus a second USB drive then you might need to swap over the USB devices in the USB sockets - it’s trying to boot from the wrong one, hence the “Unable to mount root fs” error.