Ok, then get rid of the base and use a raft. That will fix a number of issues.
Stray Edges: These are lines that don't connect to anything. They don't form faces or surfaces. They just stick out going nowhere. Everything must form a face. And all faces must be connect to form a solid object (aka Manafold)
Surface Borders: These are edges of a surface (or face) that doesn't connect to another face. A face is a two-dimensional object and by connecting all faces together, it forms a 3-dimensional object that can be printed. A Face that has a border means that one or more edges of that face doesn't connect to anything. So it just a floating face.
Face Holes: This is pretty much like it sounds. Its a hole in a face. Which also results in a Surface Border. You can form holes in objects by joining faces to form a hole, but you can't have just a hole in a face. Hope that makes sense.
Internal Face Edges: This can usually be overcome in Cura (ie: Cura can usually print objects with this error, but its better to fix it). A face has two sides: inside and outside. This helps tell the slicer (Cura) what to fill in and what to make a outside surface. When you have faces facing the wrong direction, it can confuse things up.
There are apps on the internet, as well as some that can be downloaded to help repair your object. Make Printable is just one of them:
Hope this helps.
Thank you very much fornal your effort!!!!!
I partly repaired my design (indead, I made a mesh out of it due to many adjustments) and partly by "make it Printable" What an amazing aid is this program.
I am Printing now. again many thanks