[BUG] Vulkan backend issues

[Violet-Iolite]

There seems to be an issue that makes it so the app can't communicate with the Vulkan backend even when Vulkan is functional. The error is instant when starting a generation.

Important information:

• I'm using a AMD Radeon RX 470 (8GB version);
• I'm running the GUI Version 2.7 Ubuntu 24.04 (.deb), as I'm on Linux Mint;
• I installed the libraries
• I tried to run it via CPU with the AVX2 backend and that seems to work pretty well, pointing to an issue with the Vulkan version of the app.
• The Vulkan backend works with other AI apps that support it, like KoboldCPP, so it is not a Vulkan issue.
• The errors I've got, with the v1-5-pruned-emaonly.safetensors model as a test were:
  An error occurred while starting the generation process. Error accessing background process. Please try again.

[fszontagh]

@Violet-Iolite please attach these log files:

~/.stablediffusiongui/sd_ui_data/app.log
~/.stablediffusiongui/sd_ui_data/diffuser.log

Please make attention to these log files may can contains sensitive data.

[AnnoyingTechnology]

@Violet-Iolite have you switched to another StableDiffusion frontend that supports vulkan ? If so, I'm interested.

[vivalenta]

~/.stablediffusiongui/sd_ui_data/diffuser.log

[2025-10-05 14:14:42]: StableDiffusionGUI 0.2.7 3aab399 started
[2025-10-05 14:14:42]: Starting external process: /usr/bin/stablediffusiongui_diffuser libstable-diffusion_avx512.so /home/wuddi/.stablediffusiongui/sd_ui_data/diffuser.log
[2025-10-05 14:14:42]: Loaded PRESETS: 0
[2025-10-05 14:14:42]: Loaded PROMPT_TEMPLATES: 0
[2025-10-05 14:14:42]: Loaded CHECKPOINT: 0
[2025-10-05 14:14:42]: Loaded LORA: 0
[2025-10-05 14:14:42]: Loaded VAE: 0
[2025-10-05 14:14:42]: Loaded TAESD: 0
[2025-10-05 14:14:42]: Loaded CONTROLNET: 0
[2025-10-05 14:14:42]: Loaded ESRGAN: 0
[2025-10-05 14:14:42]: Loaded EMBEDDING: 0
[2025-10-05 14:15:29]: Loaded CHECKPOINT: 1
[2025-10-05 14:15:29]: Loaded LORA: 0
[2025-10-05 14:15:29]: Loaded VAE: 0
[2025-10-05 14:15:29]: Loaded TAESD: 0
[2025-10-05 14:15:29]: Loaded CONTROLNET: 0
[2025-10-05 14:15:29]: Loaded ESRGAN: 0
[2025-10-05 14:15:29]: Loaded EMBEDDING: 0
[2025-10-05 14:15:29]: Loaded PRESETS: 0
[2025-10-05 14:15:29]: Loaded PROMPT_TEMPLATES: 0

~/.stablediffusiongui/sd_ui_data/diffuser.log

2025-10-05 14:14:42 [INFO]: Logging initialized. Log file: /home/wuddi/.stablediffusiongui/sd_ui_data/diffuser.log
2025-10-05 14:14:42 [INFO]: Starting with shared memory size: 16777216
2025-10-05 14:14:42 [ERROR]: Cannot load shared library: libstable-diffusion_avx512.so
2025-10-05 14:14:42 [INFO]: Logging initialized. Log file: /home/wuddi/.stablediffusiongui/sd_ui_data/diffuser.log
2025-10-05 14:14:42 [INFO]: Starting with shared memory size: 16777216

Instaled:
dpkg-query -l |grep stablediffusion

ii  libstablediffusion-vulkan-fbd42b6              0.2.7-Ubuntu24.04                          amd64        Stable Diffusion C++ Desktop Gui
ii  stablediffusiongui                             0.2.7-Ubuntu24.04                          amd64        Stable Diffusion C++ Desktop Gui

[fszontagh]

~/.stablediffusiongui/sd_ui_data/diffuser.log

2025-10-05 14:14:42 [INFO]: Logging initialized. Log file: /home/wuddi/.stablediffusiongui/sd_ui_data/diffuser.log
2025-10-05 14:14:42 [INFO]: Starting with shared memory size: 16777216
2025-10-05 14:14:42 [ERROR]: Cannot load shared library: libstable-diffusion_avx512.so
2025-10-05 14:14:42 [INFO]: Logging initialized. Log file: /home/wuddi/.stablediffusiongui/sd_ui_data/diffuser.log
2025-10-05 14:14:42 [INFO]: Starting with shared memory size: 16777216

Instaled: dpkg-query -l |grep stablediffusion

ii  libstablediffusion-vulkan-fbd42b6              0.2.7-Ubuntu24.04                          amd64        Stable Diffusion C++ Desktop Gui
ii  stablediffusiongui                             0.2.7-Ubuntu24.04                          amd64        Stable Diffusion C++ Desktop Gui

Thank you for the logs.

In SDGUI, there is a hardware detection step that runs when the application starts. It tries to find the best available hardware on your system in the following order: NVIDIA → VULKAN → CPU.

The error message indicates that the GUI attempted to load the AVX512 library because no compatible GPU was detected, so it fell back to using the CPU. However, your operating system doesn’t have the libstablediffusion-avx512-fbd42b6 package installed, which causes the external process to fail.

You can manually force the UI to use a specific backend for diffusion. See the instructions here: Forcing a specific backend.

In your case, simply add the -vulkan parameter when launching the binary, or edit the desktop entry to include this parameter.

When you start the GUI, please check the logs to confirm that the external process starts successfully — you can also monitor this on the status bar at the bottom of the GUI.