Without a minimal reproducible code and the mesh file, it is hard to give you guidance as to what is wrong.
I am a beginner, How to solve it
from dolfin import *
from ufl import *
mesh = Mesh(‘mesh.xml’)
Define Space
V = FunctionSpace(mesh, ‘CG’, 1)
W = VectorFunctionSpace(mesh, ‘CG’, 1)
WW = FunctionSpace(mesh, ‘DG’, 0)
p, q = TrialFunction(V), TestFunction(V)
u, v = TrialFunction(W), TestFunction(W)
Introduce manually the material parameters
Gc = 2.7
l = 0.015
lmbda = 121.1538e3
mu = 80.7692e3
One would also need the xml-file, as it is clearly the xml file that is the issue here.