Sometimes the settings inside FredoCorner or Round Corner are too aggressive for the geometry.

Understanding the root cause helps you prevent the issue before it starts. The "crack top" phenomenon usually stems from three specific limitations within SketchUp's core engine.

Before blaming your model, ensure your tools are up to date. Outdated software versions are a leading cause of compatibility issues with extensions.

The perimeter of the top face is made of disconnected line segments, leading to a "mess of red and green segments" instead of a clean, single-loop calculation. 3 Ways to Fix the Crack Top Issue

If the crack has already occurred and you do not want to redo your work, you can repair the missing top mesh manually.

If your rounding radius is too large for the physical size of the top face, the curves will overlap and cause geometric self-intersection (crashing the face). Lower the radius value.

In this long-form guide, we will dissect why this crack appears, how to fix it instantly, and how to configure your plugins to prevent it from ever happening again.

Let me know these details, and we can find the quickest way to get your model perfectly smooth. Share public link

The extension provides three primary modes accessible via a toolbar:

Hold the to soften and smooth the new line so it blends seamlessly. How to Prevent Future Cracks