Do you know how to convert surface to solid?
Convert surface to solid is pretty easy. You need to have enclosed surface and then use function Close Surface in Part design workbench. The result is solid.
And what if you get the error message like this? What does it means?
Even, it seems to be your surface is enclosed, it´s not. But how to find where it´s open?
Recheck your surface again.
Switch back to the GSD workbench, then select operation Boundary and click on the surface. Operation will create boundary all around the opened contour (green marked). But keep on mind, this trick doesn’t help you to close surface, it will help you to analyse, on which region of your surface you should focus. Then it´s easier to enclose surface.
If your surface is enclosed, CATIA cannot create any boundary. CATIA will show update error: