webui-user.bat file and add --no-half --no-half-vae to the COMMANDLINE_ARGS line. This forces the software to use full-precision math, bypassing the hardware bug causing the blackout.You’ve waited 20 minutes for a complex prompt to render, the progress bar hits 100%, and… nothing. Just a black square. It’s the “Blue Screen of Death” for the AI age. I’ve helped dozens of users debug this on everything from GTX 1660s to high-end RTX cards. The problem isn’t your prompt; it’s how your graphics card talks to the software.
1. The “Magic” Command Line Fix
Most black screen issues stem from the GPU trying (and failing) to use “half-precision” floating-point numbers to save memory. Some cards, especially the GTX 16xx series, are notoriously bad at this. We need to tell Stable Diffusion to stop cutting corners.
The Fix:
- Navigate to your Stable Diffusion folder.
- Right-click
webui-user.batand select Edit. - Find the line that says
set COMMANDLINE_ARGS=. - Add the following:
--no-half --precision full
Save the file and relaunch. This will increase VRAM usage slightly, but it brings your images back from the void.
The secret to fixing 90% of black screen errors lies in this one simple file edit.
2. The VAE Culprit
If the main generation works but the image turns black at the very last second, your VAE (Variational Autoencoder) is to blame. This component decodes the latent image into pixels. If it glitches, you get a black output.
The Fix: Add --no-half-vae to your command line arguments. This forces only the VAE to run in high precision, which is often a better compromise than running the whole model in full precision.
3. Driver & Xformers Check
Efficiency is key. If you are running an NVIDIA card, you should be using xformers. Not only does it speed up generation, but it can also sometimes bypass the precision errors, causing black screens. If you haven’t installed it, add --xformers to your command line args, and the WebUI will try to install it on launch.
Optimization isn’t optional; installing xformers can stop the black screens and speed up your renders.
Also, check your NVIDIA drivers. I recently had a rig start outputting black screens after a driver update. Rolling back to the “Studio” driver branch often fixes stability issues that the “Game Ready” drivers introduce.
Seeing that first clear image after hours of black squares is the best feeling in the world.
Common Questions
Why does Stable Diffusion generate black images?
The most common cause is the GPU’s inability to handle half-precision (FP16) calculations correctly. This often happens on GTX 16xx series cards and some older hardware. Adding ‘–no-half’ to your command line arguments usually fixes it.
What does –no-half-vae do?
This argument forces the Variational Autoencoder (VAE) to run in full precision (FP32) instead of half precision. It fixes black images that occur specifically during the final decoding step of image generation.
