PCG error

When I run my model I get the following error:

PCG has a matrix with 610th diagonal element <= 0.

Please may you explain what it means?

Thanks!

Hello

I have the same error (with 573 elements), can you help me please ?

Thank everybody

Your information, I have to say, and then it turns out that it is true.

The diagonal in the matrix must not be <= 0. There are several possible reasons for negative entries along the principal diagonal of the matrix.
1. Strong contrasts in material properties of adjacent elements. Try to refine the mesh horizontally/vertically.
2. Topological errors of the mesh as triggered inconsistent input data (e.g. overlapping elements/element edges, wrong numeration of the nodes).