Mesh errors are defects in the triangle mesh of an STL file that violate its geometric integrity. The most common are open edges (missing watertightness), self-intersections, inverted or inconsistent normals, disconnected components and isolated fragments. Mesh errors originate in scanning, design and export, and make a volume ambiguous or unreadable for CAM software.
Are mesh errors the same as manufacturing errors?
No. Mesh errors affect the file, manufacturing errors affect the part. A file without mesh errors can still be unmillable, for example due to insufficient wall thickness or undercuts.
Learn more: Watertight and intersection checks in Mill Check