Ollama SIGSEGV Crash in MLX VAE Decode on M4 Pro macOS

What this error means

SIGSEGV addr=0x0 during VAE decode after diffusion steps is a Ollama failure pattern reported for developers trying to fix ollama sigsegv crash during image generation vae decode on apple silicon. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Active GitHub issue on ollama/ollama (May 2026). x/z-image-turbo model completes 9/9 diffusion steps then crashes with SIGSEGV addr=0x0 during VAE decode on M4 Pro 64GB macOS 26.4.1 with Ollama 0.23.2. Logs show mlx runner subprocess termination after the crash.

Common causes

• Ollama users running diffusion models on M-series Macs experience reproducible SIGSEGV crashes after all diffusion steps complete, during the VAE decode phase. The error message is opaque (‘signal: segmentation fault’) and developers need specific workarounds for MLX backend on macOS.
• Active GitHub issue on ollama/ollama (May 2026). x/z-image-turbo model completes 9/9 diffusion steps then crashes with SIGSEGV addr=0x0 during VAE decode on M4 Pro 64GB macOS 26.4.1 with Ollama 0.23.2. Logs show mlx runner subprocess termination after the crash.

Quick fixes

1. Confirm the exact error signature matches SIGSEGV addr=0x0 during VAE decode after diffusion steps.
2. Check the Ollama account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/ollama/ollama/issues/16093

Evidence note: Active GitHub issue on ollama/ollama (May 2026). x/z-image-turbo model completes 9/9 diffusion steps then crashes with SIGSEGV addr=0x0 during VAE decode on M4 Pro 64GB macOS 26.4.1 with Ollama 0.23.2. Logs show mlx runner subprocess termination after the crash.

Related errors

• Ollama MLX backend out of memory on Apple Silicon
• Ollama diffusion model crash exit code 139

FAQ

What should I check first?

Start with the exact SIGSEGV addr=0x0 during VAE decode after diffusion steps text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Ollama workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without SIGSEGV addr=0x0 during VAE decode after diffusion steps.