I’m trying to install Debian Jessie on a server which doesn’t have any graphic card.
When I boot from usb, I can see the main installation prompt but after that it gives following warning:
Undefined video mode number: 314
Press <ENTER> to see video modes available, <SPACE> to continue, or wait 30 sec
and when I press to continue, it just hangs, kernel doesn’t boot.
Is there any special boot iso image for Debian to install over serial console?
You don’t need a custom iso image, standard Debian Jessie image supports installation over serial port too.
But, you have to give additional boot parameters for kernel which will be used to boot into installation system.
When you see the first prompt, press H to switch help menu. This is required to give special boot parameters.
You will see following prompt:
Press F2 through F10 for details, or ENTER to boot:
Now, give following parameters and press ENTER
install vga=off console=ttyS0,115200n8
If you have multiple serial ports you may have to change ttyS0 to related serial port device name or baudrate parameters but most of the case, it will be ttyS0 and 115200n8 as here.