Mike Rife
Ansys Employee

that style of error comes from Ansys LS-Dyna so I take it you are using an older version of MAPDL to solve this. Does the material have a poissons ratio or incompressibility factor defined (not sure which material model is being used)? If not try defining that. If you don't have a reference for the Poissons ratio or any data to find the incompressibility you could just take an educated guess. Maybe start with PR = 0.499 just to get past the time step = zero error then go from there.

Mike