After 2 years of working with 2017.2 version, finally I decided to move to the 2019 version. I have a code that used to work fine in the previous version but I am getting AttributeError in 2019 version that seems to appear in the last line while interpolation. Here is the code:

from dolfin import *
#Initial value
first = 150
second = 180
mesh = UnitSquareMesh(10, 10)
Element = FiniteElement("CG", mesh.ufl_cell(), 1)
V = FunctionSpace(mesh, Element)
# Previous solution
class IC(UserExpression):
    def __init__(self, **kwargs):
        self.FIRST = kwargs["FIRST"]
        self.SECOND = kwargs["SECOND"]
    def eval(self, value, x):
        if  x[0] >= 0.02425- DOLFIN_EPS and x[0] <= 0.02575+ DOLFIN_EPS and (x[1] >= 0.015- DOLFIN_EPS ) and (x[1] <= 0.035+ DOLFIN_EPS ):
            value[0] = self.FIRST
        else:
            value[0] = self.SECOND
IC_2 = IC(FIRST = first, SECOND = second,  degree=0)
# Previous solution
Previous_Solution = interpolate(IC_2, V)
This is the error:
Traceback (most recent call last):
  File "/home/Desktop/0TEST/NEW.py", line 31, in <module>
    Previous_Solution = interpolate(IC_2, V)
  File "/usr/lib/python3/dist-packages/dolfin/fem/interpolation.py", line 73, in interpolate
    Pv.interpolate(v)
  File "/usr/lib/python3/dist-packages/dolfin/function/function.py", line 363, in interpolate
    self._cpp_object.interpolate(u._cpp_object)
AttributeError: 'IC' object has no attribute '_cpp_object'
I am not getting error if I remove the last line but I need to do the interpolation.

Thanks in advance for your help.
              
Thanks for the reply. However that was not the fix for this issue. It raises another error:
RuntimeError: Invalid keyword argument

Anyways, I figured it out. Here is the solution for those who may encounter the same issue:
from dolfin import *
#Initial value
first = 150
second = 180
mesh = UnitSquareMesh(10, 10)
Element = FiniteElement("CG", mesh.ufl_cell(), 1)
V = FunctionSpace(mesh, Element)
# Previous solution
class IC(UserExpression):
    def __init__(self, **kwargs):
        super().__init__(degree=kwargs["degree"])
        self.FIRST = kwargs["FIRST"]
        self.SECOND = kwargs["SECOND"]
    def eval(self, value, x):
        if  x[0] >= 0.02425- DOLFIN_EPS and x[0] <= 0.02575+ DOLFIN_EPS and (x[1] >= 0.015- DOLFIN_EPS ) and (x[1] <= 0.035+ DOLFIN_EPS ):
            value[0] = self.FIRST
        else:
            value[0] = self.SECOND
    def value_shape(self):
        return ()
IC_2 = IC(FIRST = first, SECOND = second,  degree=0)
# Previous solution
Previous_Solution = interpolate(IC_2, V)