title: ValueError: Dataframe must have columns "ds" and "y" with the dates and values respectively
body: <p>I have created my data source with ds and y format and am still receiving error as above...please see below code</p>
  <pre><code>    import pandas as pd
      import numpy as np
      import pystan
      from fbprophet import Prophet
      import matplotlib.pyplot as plt
  
      plt.style.use(&quot;fivethirtyeight&quot;)
      df = pd.read_csv(r'C:\Users\sussmanbl\Desktop\fb prophet ar historical2.csv')
      df['ds'] = pd.to_datetime(df['ds'])
      print(df.head())
      df.dtypes
      plt.figure(figsize=(12,8))
      plt.plot(df.set_index('ds'))
      plt.legend(['AR'])
      m1 = Prophet(weekly_seasonality=True)
      m1 = Prophet(daily_seasonality=True)
      m1.fit(df)
      future = m1.make_future_dataframe(periods=90)
      future.tail().T
      forecast = m1.predict(future)
      forecast[['ds', 'yhat', 'yhat_lower', 'yhat_upper']].tail()
      fig1 = m1.plot(forecast)
      fig2 = m1.plot_components(forecast)
  
      runfile('C:/Users/sussmanbl/Desktop/Modelling/FB Prophet AR Historical.py', 
      wdir='C:/Users/sussmanbl/Desktop/Modelling')
      Reloaded modules: stanfit4anon_model_ad32c37d592cdbc572cbc332ac6d2ee2_4431954053790800620
      ds y
      0 2017-01-03 10
      1 2017-01-04 39
      2 2017-01-05 19
      3 2017-01-06 12
      4 2017-01-09 11
  </code></pre>
  <h2>Error:</h2>
  <pre class="lang-py prettyprint-override"><code>Traceback (most recent call last):
  
  File &quot;&quot;, line 1, in
  runfile('C:/Users/sussmanbl/Desktop/Modelling/FB Prophet AR Historical.py', 
  wdir='C:/Users/sussmanbl/Desktop/Modelling')
  
  File &quot;C:\Users\sussmanbl.conda\envs\stan_env\lib\site- 
  packages\spyder_kernels\customize\spydercustomize.py&quot;, line 827, in runfile
  execfile(filename, namespace)
  
  File &quot;C:\Users\sussmanbl.conda\envs\stan_env\lib\site- 
  packages\spyder_kernels\customize\spydercustomize.py&quot;, line 110, in execfile
  exec(compile(f.read(), filename, 'exec'), namespace)
  
  File &quot;C:/Users/sussmanbl/Desktop/Modelling/FB Prophet AR Historical.py&quot;, line 17, in
  m1.fit(df)
  
  File &quot;C:\Users\sussmanbl.conda\envs\stan_env\lib\site-packages\fbprophet\forecaster.py&quot;, line 
  1082, in fit
  
  'Dataframe must have columns &quot;ds&quot; and &quot;y&quot; with the dates and '
  
  ValueError: Dataframe must have columns &quot;ds&quot; and &quot;y&quot; with the dates and values respectively.
  </code></pre>
  <pre><code>    df.dtypes
      Out[46]:
      ds datetime64[ns]
      y int64
      dtype: object
  </code></pre>
  <p>i have formatted the source data to be in ds and y format.  the dates are in proper format as are the values.  im not sure what the code or the source data is missing that is causing the value error to come up</p>