Dear Jia, I am not sure what you mean - maybe a bump? Can you send some screenshots, your model, etc. (Troubleshooting, 2.1.1)?
Just guessing: you may be interested in Troubleshooting, 2.1.19 Problems reaching convergence and understanding ATENA convergence parameters or/and 2.4.6 Floating point problems - Division by zero, Loss of >7 digits on the matrix diagonal, CCFEModelExc: CCPardiso solver error: zero pivot, Warning: Sign of diagonal changed when reducing equation, Floating point exception: Multiple floating points traps, Zero or negative jacobian, InvertA: zero determinant, CCMaterials Extended AExc: CC5ParamYield F: project_stress_on_f_division by zero, and similar.
Regards.