title: fbprophet Error : AttributeError: 'StanModel' object has no attribute 'fit_class'AttributeError: 'StanModel' object has no attribute 'fit_class'
body: <p>I am trying to use fbprophet have installed all required packages. Please refer to below package details.</p>
  <pre><code>Requirement already satisfied: fbprophet in c:\programdata\anaconda3\lib\site-packages (0.7.1)
  Requirement already satisfied: Cython&gt;=0.22 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (0.29.21)
  Requirement already satisfied: cmdstanpy==0.9.5 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (0.9.5)
  Requirement already satisfied: pystan&gt;=2.14 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (2.19.1.1)
  Requirement already satisfied: numpy&gt;=1.15.4 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (1.19.2)
  Requirement already satisfied: pandas&gt;=1.0.4 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (1.1.3)
  Requirement already satisfied: matplotlib&gt;=2.0.0 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (3.3.2)
  Requirement already satisfied: LunarCalendar&gt;=0.0.9 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (0.0.9)
  Requirement already satisfied: convertdate&gt;=2.1.2 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (2.2.0)
  Requirement already satisfied: holidays&gt;=0.10.2 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (0.10.4)
  Requirement already satisfied: setuptools-git&gt;=1.2 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (1.2)
  Requirement already satisfied: python-dateutil&gt;=2.8.0 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (2.8.1)
  Requirement already satisfied: tqdm&gt;=4.36.1 in c:\programdata\anaconda3\lib\site-packages (from fbprophet) (4.50.2)
  Requirement already satisfied: pytz&gt;=2017.2 in c:\programdata\anaconda3\lib\site-packages (from pandas&gt;=1.0.4-&gt;fbprophet) (2019.3)
  Requirement already satisfied: pillow&gt;=6.2.0 in c:\programdata\anaconda3\lib\site-packages (from matplotlib&gt;=2.0.0-&gt;fbprophet) (8.0.1)
  Requirement already satisfied: pyparsing!=2.0.4,!=2.1.2,!=2.1.6,&gt;=2.0.3 in c:\programdata\anaconda3\lib\site-packages (from matplotlib&gt;=2.0.0-&gt;fbprophet) (2.4.7)
  Requirement already satisfied: cycler&gt;=0.10 in c:\programdata\anaconda3\lib\site-packages (from matplotlib&gt;=2.0.0-&gt;fbprophet) (0.10.0)
  Requirement already satisfied: kiwisolver&gt;=1.0.1 in c:\programdata\anaconda3\lib\site-packages (from matplotlib&gt;=2.0.0-&gt;fbprophet) (1.3.0)
  Requirement already satisfied: certifi&gt;=2020.06.20 in c:\programdata\anaconda3\lib\site-packages (from matplotlib&gt;=2.0.0-&gt;fbprophet) (2020.6.20)
  Requirement already satisfied: ephem&gt;=3.7.5.3 in c:\programdata\anaconda3\lib\site-packages (from LunarCalendar&gt;=0.0.9-&gt;fbprophet) (3.7.7.1)
  Requirement already satisfied: pymeeus&lt;=1,&gt;=0.3.6 in c:\programdata\anaconda3\lib\site-packages (from convertdate&gt;=2.1.2-&gt;fbprophet) (0.3.7)
  Requirement already satisfied: korean-lunar-calendar in c:\programdata\anaconda3\lib\site-packages (from holidays&gt;=0.10.2-&gt;fbprophet) (0.2.1)
  Requirement already satisfied: six in c:\programdata\anaconda3\lib\site-packages (from holidays&gt;=0.10.2-&gt;fbprophet) (1.15.0)
  </code></pre>
  <p>But while fitting model I am getting error &quot;AttributeError: 'StanModel' object has no attribute 'fit_class'&quot;</p>
  <p>Can anyone please help me how to resolve this error</p>
  <p>Also getting below warning when tried to load model</p>
  <pre><code>model = Prophet()
  WARNING:pystan:No module named 'stanfit4anon_model_f5236004a3fd5b8429270d00efcc0cf9_4174861822198299618'
  WARNING:pystan:Something went wrong while unpickling the StanModel. Consider recompiling.
  </code></pre>