Proxmox 7.1 - Can't boot if screen unppluged

[DarkArshyn]

Hi everyone,

I have a small and disturbing problem. I have an old PC that I use as a hypervisor for my classes to run small VMs remotely.

Previously I had Windows Server 2019 natively installed on it and was running my VMs with VMware Workstation. I was able to boot the PC without any problem, without any device connected (except of course the RJ45 cable), and accessed it via RDP.

I have since decided to switch to Proxmox because it is lighter and I think more adapted to my expectations. The installation went well but I have a problem. If I don't connect a screen, Proxmox doesn't want to start, I don't have access to the web interface at all and except for the local IPv6 address I don't have access to IPv4. However, when I plug in the screen, everything works correctly

I find this problem very annoying as I didn't have it at all under Windows Server. This is not a BIOS problem as I have not made any changes, the problem is with Proxmox itself.

Is there any way to fix this problem please ?

The PC model is : HP EliteDesk 800 G1 USDT

PS: I'm french so sorry for my bad english

 

[Dunuin]

Doesn't really fix your problem but a workaround might be a dummy plug (costs less than 10€). That will emulate a monitor so your GPU thinks a monitor is connected.

 

[DarkArshyn]

I have already tried to connect a cable without a monitor behind it, it doesn't boot without it. If there is no solution I guess I'll have to go to something else like ESXi

 

[Dunuin]

I have already tried to connect a cable without a monitor behind it, it doesn't boot without it. If there is no solution I guess I'll have to go to something else like ESXi

A dummy plug isn't just a cable. It will emulate the communication of the monitor too so the host really thinks there is a monitor connected.

 

[DarkArshyn]

Does it exist in DisplayPort version ? I don't have an HDMI port

I think it comes from Proxmox since I don't have the problem at all with Windows Server, it's probably a story of configuration in a file but I don't know enough about it

 

[Dunuin]

Does it exist in DisplayPort version ? I don't have an HDMI port

I think it comes from Proxmox since I don't have the problem at all with Windows Server, it's probably a story of configuration in a file but I don't know enough about it

Yes, dummy plugs are available for all ports. But it is really only a workaround. You really should try to find out first why it isn't working without a monitor attached. I would guess you just got some quirky hardware because PVE is designed to run headless and in general no attached monitor is required.

If you think PVE is the problem you can also try to install a normal Debian 11 (Bullseye) as another workaround and look if it is working without a monitor. If it works you can than install PVE ontop of that Debian. The PVE package will then turn that Debian into a PVE, install all required packages and replace the Debian kernel with the custom PVE kernel (based on the Ubuntu LTS kernel). That is sometimes useful for very old hardware. In that case you are booting the machine like a normal Debian instead of using the proxmox-boot-tool you would get when installing PVE from the PVE ISO. But the debian installer doesn't support ZFS for your system disks. In case you want raid1 you could only use HW raid or mdadm SW raid with etx/xfs/LVM ontop.

 

[DarkArshyn]

The problem comes from Linux in general, I installed Debian 11 without anything on it with just an SSH server. Screen plugged in no problem everything works I have SSH access. Screen unplugged nothing works anymore

So I'll see if I can go to ESXi or back to Windows Server, it's a shame

 

[piton]

I have the same issue on T620 and proxmox 7.2

 

[leo1in88]

I got the same problem. Im using PC with intel i5 6600 and gtx 730. When i unplug the monitor, I can not connect to the host machine from other computers.

 

[noel.]

When i unplug the monitor, I can not connect to the host machine from other computers.

Can you reach your host using ssh as well as the web interface before you unplug the monitor? Can you reach either the web interface or the host via ssh after unplugging the monitor? Are you unplugging the monitor before you boot or after you have booted and are all set up?

If your problem is the same (i.e. if you try to boot without a monitor attached, the host can't boot) there are the options Dunuin mentioned above:

1. Try with a Debian install and install proxmox ve on top of that
2. buy a dummy plug

Not all motherboards support headless mode, you should look up if yours does. There might also be a BIOS setting to enable it.

 

[leo1in88]

Can you reach your host using ssh as well as the web interface before you unplug the monitor? Can you reach either the web interface or the host via ssh after unplugging the monitor? Are you unplugging the monitor before you boot or after you have booted and are all set up?

If your problem is the same (i.e. if you try to boot without a monitor attached, the host can't boot) there are the options Dunuin mentioned above:

1. Try with a Debian install and install proxmox ve on top of that
2. buy a dummy plug

Not all motherboards support headless mode, you should look up if yours does. There might also be a BIOS setting to enable it.

Hi i can access to my PC with or without the monitor. The problem is when i installed Proxmox 6 its dont show any error when i turn off the system through command. But the Fan of CPU still running. When i instal Proxmox 7, turn of the System its show the error: systemD-shutdown [1]: failed to finalized DM devices, ignoring" and yes fan of CPU still running. WHen i install Proxmox 8, i can not do that.
ANd one thing to noticed is when i detached the Disk and bring it to other PC, its running without any error.

 

[noel.]

If your computer is turned all the way off and the fans are still running, that sounds like a Bios or hardware issue to me. Especially when you say that it works with the same disk installed in a different machine.
You could try installing a different disk with a different OS (E.G. Debian or Fedora) and see if you still get those issues.
Otherwise things like updating/flashing your bios to the newest version, checking the debug-leds on your motherboard (if it has any), checking if the cpu is seated correctly and no pins are bent in the socket, seeing which fans are still running (gpu, cpu or casefans). All of this is outside of my official Proxmox knowledge though, I take no liability if that doesn't work or, e.g. while reseating your cpu, you bend pins or something.

WHen i install Proxmox 8, i can not do that.

What can't you do?

 

[leo1in88]

If your computer is turned all the way off and the fans are still running, that sounds like a Bios or hardware issue to me. Especially when you say that it works with the same disk installed in a different machine.
You could try installing a different disk with a different OS (E.G. Debian or Fedora) and see if you still get those issues.
Otherwise things like updating/flashing your bios to the newest version, checking the debug-leds on your motherboard (if it has any), checking if the cpu is seated correctly and no pins are bent in the socket, seeing which fans are still running (gpu, cpu or casefans). All of this is outside of my official Proxmox knowledge though, I take no liability if that doesn't work or, e.g. while reseating your cpu, you bend pins or something.

What can't you do?

I dont know. It seems stuck in command line when install newest proxmox version.

 

[noel.]

I'd still would guess that it's something with your BIOS or maybe hardware, especially since you say that when you take the disk out and install it in a different machine, that it works.

I dont know. It seems stuck in command line when install newest proxmox version.

Are you saying that the machine hangs when you try to update it to the newest version via the command line? or that, on the newest version, the machine gets stuck when you try to turn if off via the commandline?

If I understood correctly, it's the second one, right? If so, what command do you run to turn off the computer? If there are vms/containers still running, it might just take a while. You can check the boot logs using journalctl -b -0 to see the logs of the current boot and journalctl -b -1 to see the logs of the previous boot. You can also check your logfiles withcat /var/log/syslog and then check around the time that you powered off to see if anything errors. Please attach the output of these logs and I can take a look