Check your initramfs if it's missing /dev/null or /dev/console, this is likely the reason.
If you want all actual devices to be created you could also enable devtmpfs in your kernel (.config) and mount like this during init:
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
mount -t devtmpfs none /dev
But note devtmpfs will not create /dev/null or /dev/console for........