Why is my 3D view or toolpath preview black / garbled?

Why this happens

This is a graphics-stack problem, not file corruption:

• Outdated or broken GPU drivers (the majority of cases)
• Flaky OpenGL/DirectX support. Some AMD configurations are reported as problem cases, and NVIDIA is generally reported to be the safest choice for this software
• Virtual machines always use slow software rendering
• A renderer setting mismatch after a Windows or driver update

The fix

1. Update the graphics driver first. Get it from the GPU maker's site (NVIDIA/AMD/Intel), not just Windows Update. This alone fixes most cases.
2. Toggle the fallback: Edit > Options > 3D View Settings > Use Software Renderer = Yes, then restart the program. The option switches from hardware GPU rendering to software (CPU) rendering, which the official documentation says can be preferable when GPU capability is limited or there are compatibility issues. If the view comes back, the GPU or driver was the problem. You can retry hardware rendering after the next driver update.
3. Laptops with dual GPUs: force the discrete GPU for the program's executable in the NVIDIA/AMD control panel (integrated GPUs sometimes grab the app).

Pro tips

• Software rendering works but is slow on big 3D jobs. Treat it as a diagnostic or fallback, not the permanent fix.
• If only the material shading looks wrong (not black), that is the preview material and lighting settings, not the renderer.
• Official documentation: Options Dialog
• Software maker's user forum: black preview thread
• Software maker's user forum: graphics driver thread
• Software maker's user forum: renderer thread