Maybe you need to install the firmware from backports.

apt-get -t jessie-backports install firmware-iwlwifi

Yes, go with backports. Disable ascii. All the devs have been focused on getting jessie ready, and not much work has been done on ascii.

apt-get -t jessie-backports install linux-image-4.9.0-0.bpo.2-amd64

Trust the Force, Luke. You are correct.
I just booted with 'nomodeset' and redshift no longer works. Neither does my brightness script that I've been using.

Make sure randr is installed. Check in synaptic. You can also see what methods are available to redshift with

redshift -m list

I can start 'redshift-gtk' on the command line if I give it my latitude and longitude. It works, it puts an icon in the system tray, and I can get an information window from that.

I'm not sure. I know that live-sdk uses some of the same libraries as the devuan sdk that's used for building all the other images, so at least part of the decision was for consistency. I also know that early on, it was impossible to build an iso with live build-that didn't include systemd. I just tried the version of live-build in jessie, and it looks like it was neglected. It still uses debian repos. I just changed that and it's running. I'll know more in a little while.

I'm hoping Ozi will say something here. He uses live-build and knows more about it.

Edit: This is with version 4.0.3-1+devuan2, which looks to be the only one in jessie, ascii and ceres.

The following packages have unmet dependencies:
 live-config-systemd : Depends: systemd but it is not installable
                       Recommends: dbus but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

@FOSSuser: Good call.

@hughparker1: the correct locale to choose is en_GB

OK, my problem is all better now. I could not create users or groups. Went through the vaious software fixes proposed in similar posts, and none of them seemed to apply. Problem went away with a complete poweroff and blowing out dust. I can now create users and groups, and mysql-server installed without any trouble.

I have one install that has mysql-server for one app that needs it for its database. It only gets used from localhost, and it works fine. I just upgraded it after many months, and it still works.

I just tried to install mysql-server on my main box, and it's failing with this error message:

dpkg: error processing archive /var/cache/apt/archives/mysql-server-5.5_5.5.55-0+deb8u1_amd64.deb (--unpack):
 subprocess new pre-installation script returned error exit status 1

Attempting to add the group manually:

groupadd -g 121 mysql
groupadd: failure while writing changes to /etc/group

This is strange. I got the same error a few days ago trying to install something, but that was in a chroot, and I needed to make the bind-mounts with sys, dev and proc. Right now, I'm not in a chroot. I'm installing directly on hardware in the running system. If someone else wants to try, you can let me know if the problem is just with my setup.

I don't think it's a file permission problem:

-rw-r--r-- 1 root root 904 Mar  8 18:38 /etc/group

When you start synaptic from the menu, you should get a window that asks for a password. If you set up the system to use a root account, use the root password, and if you set it up for sudo, use your password. If you're not getting the pop-up window for authentication, the start it from a terminal like you did until that issue is solved.

For the grub problem. You're right. Editing the config on devuan won't help if debian is in charge of boot. I can think of three ways to fix it.
1. Boot into Devuan and reinstall grub-efi-amd64
2. Boot into Devuan and run 'sudo grub-install' in a terminal. (no device name needed with uefi)
    - optional for 2: run 'sudo grub-install --bootloader-id=some-name'

In either of those cases above, grub will create a bootloader and I expect it will put itself first in the list of bootloaders. Then you'll need to run update-grub to get debian in the boot menu. WARNING: I don't know this for a fact. UEFI implementations vary from manufacturer to manufacturer, so your system might not act like mine. COMMENT: I would try #2 with the bootloader-id first, and use an id name that is something other than debian, devuan or boot. Then you will know for sure that it's the one you just made.

In my system, Debian's bootloader is in /boot/efi/EFI/debian and Devuan's is in /boot/efi/EFI/devuan. There is a /boot/efi/EFI/boot/, too. I forget where that came from, and I don't use it. Whenever I install a linux and allow grub to install, it becomes first. If I change the order of the bootloaders using efibootmgr, it shows me that the boot order has changed, and then it reverts to the previous order as soon as I reboot. Yours may act differently.

3. Boot into Debian and copy the menuentry for Devuan from /boot/grub/grub.cfg into /etc/grub.d/40_custom, add nomodeset to the linux line, and run update-grub. There will be an extra entry for Devuan in the boot menu, and that one will have nomodeset in the boot command. The entry starts with the word, menuentry and ends with a closing curly brace `}' 

Read this if you haven't, re-read it if you have: http://www.rodsbooks.com/efi-bootloaders/index.html

1. Graphics card or driver. Whichever one you want to blame. You could try the proprietary driver, but if it's working ok, there's no need.

2. Yes. Add nomodeset to /etc/default/grub and then run update-grub to generate a new menu. Then you don't have to edit at boot every time.

GRUB_CMDLINE_LINUX_DEFAULT="quiet nomodeset"

At the boot menu, press 'e' to edit the boot entry. Use the arrow keys to navigate to the linux line and add the word, nomodeset to the line. Then ctrl-x to boot.

No, I haven't seen that except when I was trying to boot to console. You should not need to log in to the desktop - it should happen automatically.
It's an isohybrid image, so anything that just copies it bit by bit to the whole device should work. I don't know what Mint or Rufus does, but if Rufus needs to know that it's for uefi, then it's probably doing something about that, and it should not. If you have a running linux, you can just use dd.

Please check the following commands:

tty          #which tty are you connected to?
ps ax |grep slim       # is the display manager running?
sudo runlevel
cat .xsession-errors
sudo less /var/log/Xorg.0.log    # look for lines starting with EE

Try ctrl-alt-F7 (maybe F8 or F9) to see if that gets you to the desktop.

If slim is not running, try starting it:

sudo service slim start

Check the sha256sum to make sure the download was good.

$ sha256sum devuan_jessie_1.0.0-RC2_amd64_uefi-live.iso
ac38f0c7d983f8ce93f7b261274fef30823022707b96fc1c09f6b9a1b0c3709d  devuan_jessie_1.0.0-RC2_amd64_uefi-live.iso