Slice plugin

Hello i need some help, i had use slice plugin but it says that my object is not manifold solid and it gives me an erorr. I attached the project below pls help!
Untitle345d.skp (346.1 KB)

Fix the hole in the surface. Then it should be solid.

I tried that but i cannot do it beacuse when i do it erases the face

Fill the hole by tracing across the opening with the Line tool.

Or better, fix the surrounding geometry so it’s a smoother surface.

Untitle345d.skp (360.4 KB)

Thank you so much :grin: