I have a 4 step simulation which use the *restart option to continue from one step to the other. The steps are as follows

Implicit displacement driven simulation [Iterative solver] > Unloading step [Direct solver] > Pertubation steps > RIKS Step to attain a predefined stress state

This worked for v2017, but when I use v2021 I get the following error - ' THE RIKS PARAMETER MAY NOT BE USED WITH THE DDM SOLVER'. Any support here would be helpful.

This error does not appear if I use Direct solver in Step-1. But this solution is not practical for the larger simulations, considering the computation time.