How to use mortar contact?

In one of my simulation, I tried to use mortar type of contact. I simply changed surface-to-surface to the mortar. The following errors appear:

Is there some specific needs when using mortar?
It seems that there is a problem with depended nodes in MPC …
I checked CalculiX documentation for awareness (e.g. to be used only with static analysis) but I did not find other specifics to follow.

Thanks in advance for any advice.