problem with cyclic region of a gear in ansys mechanical

What do your mesh controls look like? From the warning, it sounds like there may be a conflict between the mesh controls on the low and high sides of your cyclic symmetry region. If you have any mesh controls set to "hard" behavior (the warning makes it sound like you do), try setting it to soft and seeing how that works. You could also try suppressing the cyclic symmetry feature, meshing, and then comparing the meshes on the low and high sides to see if and how they differ.

thank you for answer
if I change the sizing behaviour on "soft" I still have the same problem, I still have the problem even if I use no meshing method and using a bigger element size. Without the cyclic region the mesh at the low and high face is the same

There are two main issues you can run into when meshing bodies for cyclic symmetry. The first one is the Low and High region scoping.

I have resolved using "stage" in symmetry, but I still have mesh problems using a method in the mesh generation so I have to use a mesh made by tetrahedrons instead of hexahedrons