Yeah, now I’m able to reproduce the error as -
RuntimeError:
*** -------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve this issue
*** using the information listed below, you can ask for help at
***
*** fenics-support@googlegroups.com
***
*** Remember to include the error message listed below and, if possible,
*** include a *minimal* running example to reproduce the error.
***
*** -------------------------------------------------------------------------
*** Error: Unable to solve nonlinear system with NewtonSolver.
*** Reason: Newton solver did not converge because maximum number of iterations reached.
*** Where: This error was encountered inside NewtonSolver.cpp.
*** Process: 0
***
*** DOLFIN version: 2019.2.0.dev0
*** Git changeset: ubuntu
*** -------------------------------------------------------------------------
I tried couple of things like increasing maximum iterations and relax the tolerance requirements as done in this post How to increase maximum number of iterations? and I also tried easing the relaxing parameter as suggested here Default absolute tolerance and relative tolerance and also used CustomSolver() given here.
But none of them worked which led me to conclude that there might be a chance of malformed Jacobian therefore I suggest you to kindly read this post Default absolute tolerance and relative tolerance and check Jacobian once.