Repeated error test failures. May have reached a singularity.

I am using comsol 5.4. I am trying to solve a coefficient form PDE along with Electrical Circuit, Electric current and Joule heating. I am getting the following error message. "*Repeated error test failures. May have reached a singularity. Time : 0.45947452527474841 Last time step is not converged. *" What does it signifies?My meshings are Fine, Extra fine and extremely fine