Dear Daniele Click on the Solution Information folder and in the Details window, type the number 3 into the Newton-Raphson Residuals field.
Restart the solution and allow three more iterations to solve (or just run the solution from the beginning).
Under the Solution Information folder will be 3 N-R Force Residual plots. Look at the location of the maximum value. That is where you may need to have a refined mesh.
Do you have any linear elastic materials with a Poisson's Ratio above 0.45? Those can cause convergence issues which may be improved by turning on mixed u-P element formulation and changing the material to a hyperelastic material model.
Regards Peter