Hi everyone,
I have a setup that works perfectly for a Fedora VM, but an almost identical Ubuntu VM results in a "No Signal" screen after the initial boot splash. This leads me to believe my host configuration is correct and the issue is guest-specific.
**The Problem:**
* I start the Ubuntu VM.
* The Ubuntu boot logo and loading spinner appear correctly on my physically connected monitor.
* After about 5-10 seconds, the monitor loses signal and goes black.
* The VM itself continues to run in the Proxmox web UI.
* A nearly identical Fedora VM boots straight to the desktop on the same physical monitor without any issues.
**VM Configurations:**
Here are the `.conf` files for both the working (Fedora) and non-working (Ubuntu) VMs. They are nearly identical apart from the ISO, MAC address, and UUIDs.
**VM 100 (Fedora - Working) Configuration:**
```
agent: 1
boot: order=scsi0;ide2;net0
cores: 15
cpu: x86-64-v2-AES
hostpci0: 0000:0c:00,pcie=1
ide2: local:iso/Fedora-KDE-Desktop-Live-42-1.1.x86_64.iso,media=cdrom,size=2777870K
machine: q35
memory: 27048
meta: creation-qemu=9.2.0,ctime=1749493875
name: Fedora
net0: virtio=BC:24:11:B2:E9:24,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: local-lvm:vm-100-disk-0,iothread=1,size=1000G
scsihw: virtio-scsi-single
smbios1: uuid=521a1a95-1f26-4089-b847-121156b0ba88
sockets: 1
usb0: host=3-1.4
usb1: host=3-2
vmgenid: 615aaef6-c9a3-4358-a46b-a74c321ee4fd
```
**VM 101 (Ubuntu - Not Working) Configuration:**
```
agent: 1
boot: order=scsi0;ide2;net0
cores: 15
cpu: x86-64-v2-AES
hostpci0: 0000:0c:00,pcie=1
ide2: local:iso/ubuntu-25.04-desktop-amd64.iso,media=cdrom,size=6131368K
machine: q35
memory: 27048
meta: creation-qemu=9.2.0,ctime=1749547118
name: Ubuntu
net0: virtio=BC:24:11:95:AA:FD,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: local-lvm:vm-101-disk-0,iothread=1,size=1000G
scsihw: virtio-scsi-single
smbios1: uuid=e0c636bf-eb28-4000-a13c-babc122ffb85
sockets: 1
usb0: host=3-1.4
usb1: host=3-2
vmgenid: 87865094-2e7e-47c7-86ee-6c7685f6eb8c
```
---
**Troubleshooting Steps Already Taken:**
I have tried the following steps on the Ubuntu VM without success:
1. **Blacklisted `nouveau`:** Created `/etc/modprobe.d/blacklist-nouveau.conf` with `blacklist nouveau` and `options nouveau modeset=0`.
2. **Updated initramfs:** Ran `sudo update-initramfs -u` after blacklisting.
3. **Installed Proprietary Drivers:** Used `sudo ubuntu-drivers autoinstall` to install the recommended NVIDIA drivers. Rebooted after installation.
Any guidance or suggestions would be greatly appreciated. Thank you
I have a setup that works perfectly for a Fedora VM, but an almost identical Ubuntu VM results in a "No Signal" screen after the initial boot splash. This leads me to believe my host configuration is correct and the issue is guest-specific.
**The Problem:**
* I start the Ubuntu VM.
* The Ubuntu boot logo and loading spinner appear correctly on my physically connected monitor.
* After about 5-10 seconds, the monitor loses signal and goes black.
* The VM itself continues to run in the Proxmox web UI.
* A nearly identical Fedora VM boots straight to the desktop on the same physical monitor without any issues.
**VM Configurations:**
Here are the `.conf` files for both the working (Fedora) and non-working (Ubuntu) VMs. They are nearly identical apart from the ISO, MAC address, and UUIDs.
**VM 100 (Fedora - Working) Configuration:**
```
agent: 1
boot: order=scsi0;ide2;net0
cores: 15
cpu: x86-64-v2-AES
hostpci0: 0000:0c:00,pcie=1
ide2: local:iso/Fedora-KDE-Desktop-Live-42-1.1.x86_64.iso,media=cdrom,size=2777870K
machine: q35
memory: 27048
meta: creation-qemu=9.2.0,ctime=1749493875
name: Fedora
net0: virtio=BC:24:11:B2:E9:24,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: local-lvm:vm-100-disk-0,iothread=1,size=1000G
scsihw: virtio-scsi-single
smbios1: uuid=521a1a95-1f26-4089-b847-121156b0ba88
sockets: 1
usb0: host=3-1.4
usb1: host=3-2
vmgenid: 615aaef6-c9a3-4358-a46b-a74c321ee4fd
```
**VM 101 (Ubuntu - Not Working) Configuration:**
```
agent: 1
boot: order=scsi0;ide2;net0
cores: 15
cpu: x86-64-v2-AES
hostpci0: 0000:0c:00,pcie=1
ide2: local:iso/ubuntu-25.04-desktop-amd64.iso,media=cdrom,size=6131368K
machine: q35
memory: 27048
meta: creation-qemu=9.2.0,ctime=1749547118
name: Ubuntu
net0: virtio=BC:24:11:95:AA:FD,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: local-lvm:vm-101-disk-0,iothread=1,size=1000G
scsihw: virtio-scsi-single
smbios1: uuid=e0c636bf-eb28-4000-a13c-babc122ffb85
sockets: 1
usb0: host=3-1.4
usb1: host=3-2
vmgenid: 87865094-2e7e-47c7-86ee-6c7685f6eb8c
```
---
**Troubleshooting Steps Already Taken:**
I have tried the following steps on the Ubuntu VM without success:
1. **Blacklisted `nouveau`:** Created `/etc/modprobe.d/blacklist-nouveau.conf` with `blacklist nouveau` and `options nouveau modeset=0`.
2. **Updated initramfs:** Ran `sudo update-initramfs -u` after blacklisting.
3. **Installed Proprietary Drivers:** Used `sudo ubuntu-drivers autoinstall` to install the recommended NVIDIA drivers. Rebooted after installation.
Any guidance or suggestions would be greatly appreciated. Thank you