'SimSystemPosix' object has no attribute 'files'

[reb311ion]

Traceback (most recent call last):
  File "C:/Program Files/IDA 7.0/plugins/AngryIDA.py", line 287, in activate
    explore_run()
  File "C:/Users/Rebellion/Downloads/AngryIDA.py", line 506, in explore_run
    k = initial_state.posix.files[0].read_from(1)
AttributeError: 'SimSystemPosix' object has no attribute 'files'

C:\Users\Rebellion\Desktop\tools>python --version
Python 2.7.15

C:\Users\Rebellion\Desktop\tools>pip install angr
DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 wo
n't be maintained after that date. A future version of pip will drop support for Python 2.7.
Requirement already satisfied: angr in c:\python27\lib\site-packages (7.8.9.26)
Requirement already satisfied: pyvex==7.8.9.26 in c:\python27\lib\site-packages (from angr) (7.8.9.26)
Requirement already satisfied: sortedcontainers==2.0.5 in c:\python27\lib\site-packages (from angr) (2.0.5)
Requirement already satisfied: unicorn==1.0.1 in c:\python27\lib\site-packages (from angr) (1.0.1)
Requirement already satisfied: pycparser==2.18 in c:\python27\lib\site-packages (from angr) (2.18)
Requirement already satisfied: progressbar==2.3 in c:\python27\lib\site-packages (from angr) (2.3)
Requirement already satisfied: archinfo==7.8.9.26 in c:\python27\lib\site-packages (from angr) (7.8.9.26)
Requirement already satisfied: claripy==7.8.9.26 in c:\python27\lib\site-packages (from angr) (7.8.9.26)
Requirement already satisfied: GitPython==2.1.9 in c:\python27\lib\site-packages (from angr) (2.1.9)
Requirement already satisfied: mulpyplexer==0.08 in c:\python27\lib\site-packages (from angr) (0.8)
Requirement already satisfied: ailment==7.8.9.26 in c:\python27\lib\site-packages (from angr) (7.8.9.26)
Requirement already satisfied: networkx==2.1 in c:\python27\lib\site-packages (from angr) (2.1)
Requirement already satisfied: cle==7.8.9.26 in c:\python27\lib\site-packages (from angr) (7.8.9.26)
Requirement already satisfied: ana==0.05 in c:\python27\lib\site-packages (from angr) (0.5)
Requirement already satisfied: cachetools==2.1.0 in c:\python27\lib\site-packages (from angr) (2.1.0)
Requirement already satisfied: dpkt-fix==1.7 in c:\python27\lib\site-packages (from angr) (1.7)
Requirement already satisfied: futures==3.2.0; python_version == "2.7" in c:\users\rebellion\appdata\roaming\python\pyth
on27\site-packages (from angr) (3.2.0)
Requirement already satisfied: rpyc==3.3.0 in c:\python27\lib\site-packages (from angr) (3.3.0)
Requirement already satisfied: cffi==1.7.0 in c:\python27\lib\site-packages (from angr) (1.7.0)
Requirement already satisfied: capstone==3.0.5 in c:\python27\lib\site-packages (from angr) (3.0.5)
Requirement already satisfied: cooldict==1.03 in c:\python27\lib\site-packages (from angr) (1.3)
Requirement already satisfied: future==0.16.0 in c:\python27\lib\site-packages (from pyvex==7.8.9.26->angr) (0.16.0)
Requirement already satisfied: bitstring==3.1.5 in c:\python27\lib\site-packages (from pyvex==7.8.9.26->angr) (3.1.5)
Requirement already satisfied: z3-solver==4.5.1.0.post2 in c:\python27\lib\site-packages (from claripy==7.8.9.26->angr)
(4.5.1.0.post2)
Requirement already satisfied: gitdb2>=2.0.0 in c:\python27\lib\site-packages (from GitPython==2.1.9->angr) (2.0.5)
Requirement already satisfied: decorator>=4.1.0 in c:\python27\lib\site-packages (from networkx==2.1->angr) (4.3.0)
Requirement already satisfied: pefile==2016.3.28 in c:\python27\lib\site-packages (from cle==7.8.9.26->angr) (2016.3.28)

Requirement already satisfied: idalink==0.10 in c:\python27\lib\site-packages (from cle==7.8.9.26->angr) (0.10)
Requirement already satisfied: pyelftools==0.25 in c:\python27\lib\site-packages (from cle==7.8.9.26->angr) (0.25)
Requirement already satisfied: plumbum in c:\python27\lib\site-packages (from rpyc==3.3.0->angr) (1.6.7)
Requirement already satisfied: smmap2>=2.0.0 in c:\python27\lib\site-packages (from gitdb2>=2.0.0->GitPython==2.1.9->ang
r) (2.0.5)

why and how to fix it ?