Cause

The cross-section of the routed connection is smaller than the cross-section set in the connection point pattern of the part placement in the Min. wire cross-section column.

Solution

1. Increase the value of the cross-section at the routing connection (or the corresponding multi-line connection in the schematic) so that it amounts to no less than the value entered in the connection point pattern in the Min. wire cross-section column. Or, alternatively, adjust in this column the cross-section value to the cross-section of the routing connection by decreasing the value accordingly.
2. Then start a new check run.