Mesh error det J = -6904.16 is negative for element 0

I am trying to convert a simple 2d model. I created the geometry and mesh in gmsh and used gmsh2ogs to extract the mesh and boundaries for my model. I try run a heat conduction model and while loading the meshes I get the following error form OGS. Can any one suggest whats going wrong here and how to fix it? (271.2 KB)

Did you use the NodeReodering tool as well? It could be that it is just the node order which is not correct.
Alternatively, you could also try the msh2vtu tool (GitHub - dominik-kern/msh2vtu: Conversion of meshes from gmsh- to vtu-format, particularly for further use in OpenGeoSys), which I prefer because it generates also boundary meshes from physical entities.

Hi Joergbuchwald,
Thanks for the help. I did try node reordering which didn’t work either. However, using msh2vtu instead of gmsh2ogs worked a treat.