[deal.II] Output problem of DG with degree =0

Hey all, I am trying to solve a level set equation with DG. When I use degree=1, everything is ok, but when I change it to degree=0, it cannot output the results, and says: An error occurred in line <957> of file in function void dealii::DataOut_DoFData

[deal.II] Re: geometry

Daniel, In that code, I had a half circle in the right part of the coordinate axis. By writing v(1) <=0, I wanted to choose the part with negative y components from the geometry, however, The attached file has been obtained. I really do not know how I should modify the source you sent to me

[deal.II] Re: geometry

Benhour, It would be helpful if you tell us what the problem with the newly created problem is. Looking at the implementation of GridGenerator::half_hyper_ball [1], you can observe that there are cells which have vertices both with positive and negative y-components. This will likely lead to