Run time error issue

I am getting run time error when i solve the following:

fn.solve(a == L, u, bcs, solver_parameters={‘linear_solver’:‘gmres’,‘preconditioner’:‘ilu’})

Please find the error messages below:

File “/usr/lib/python3/dist-packages/dolfin/fem/”, line 220, in solve
_solve_varproblem(*args, **kwargs)
File “/usr/lib/python3/dist-packages/dolfin/fem/”, line 247, in _solve_varproblem

*** -------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve this issue
*** using the information listed below, you can ask for help at


*** Remember to include the error message listed below and, if possible,
*** include a minimal running example to reproduce the error.

*** -------------------------------------------------------------------------
*** Error: Unable to solve linear system using PETSc Krylov solver.
*** Reason: Solution failed to converge in 10000 iterations (PETSc reason DIVERGED_ITS, residual norm ||r|| = 1.694328e+01).
*** Where: This error was encountered inside PETScKrylovSolver.cpp.
*** Process: 0

*** DOLFIN version: 2019.1.0
*** Git changeset: unknown
*** -------------------------------------------------------------------------

Could you please suggest how to resolve this issue?