Hi, I was in the middle of a Boolean add operation and got the error pop-up again. I was working on the manifold and brought in a new flange with the Boolean Unite operation. Selected 'component placement/precise placement' in order to rotate the new flange, picked an edge on the manifold to use as an axis and the error message appeared. Closed/opened Alibre - repeated the operation this time selecting one of the principal axes and all is well. So it doesn't like the edge on the existing geometry for some reason. Any suggestions as to why that might be? Thanks.