Issue:

This error popped up when I tried to run a Topology Optimization using the Extrusion Constraint: Invalid combination/design curve, not all elements could be mapped.

Cause:

The section of the part along the curve has to be constant in order for the Extrusion Constraint to work properly.

Solution:

Change the starting part to have a constant thickness along the curve.

More on this topic:

• Topology Optimization Walk-through
• Topology Optimization: Geometric Constraints