I import points from a .csv and connect them with a single line. After that I Spin them 360 degrees/steps. Deselect and Reselect all vertices. Click Remove Doubles. Unfortunately the mesh is not only non Manifold but also the resulting non manifold vertices are not constant. Here a screenshot of the upper part, where one can see that not all of the vertices are non manifold.
I did the exact thing already and it worked the first time. I don't understand why it gives me this error. Any help would be great. Thanks