Kaushal Vadnere
Ansys Employee

Hi Ji Shiyu,

this warning suggests that you have overlapping boundary conditions or contacts which lead to conflicts and prevent MPC constraints from being created and cause parts to lose contacts.
To overcome this, consider relocating applied supports/boundary conditions/contacts sharing same bodies, surfaces, edges, nodes.
Refer to this article in Ansys help for more troubleshooting recommendations: One or more MPC or Lagrange Multiplier formulation based contact may have conflicts (ansys.com)