The variational inference example doesn't work


vi = model.variational(data=data_file)
09:23:52 - cmdstanpy - INFO - Chain [1] start processing
09:23:52 - cmdstanpy - INFO - Chain [1] done processing
09:23:52 - cmdstanpy - ERROR - Chain [1] error: error during processing Operation not permitted
Traceback (most recent call last):
  File "C:\Users\yliad\anaconda3\lib\site-packages\IPython\core\", line 3444, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-13-745a9131b5f1>", line 1, in <module>
    vi = model.variational(data=data_file)
  File "C:\Users\yliad\anaconda3\lib\site-packages\cmdstanpy\", line 1546, in variational
    raise RuntimeError(msg)
RuntimeError: Error during variational inference: Error in JSON parsing 


import os
from cmdstanpy.model import CmdStanModel
bernoulli_dir = os.path.join('C:\\Users\\yliad\\PycharmProjects\\BP_FA')
stan_file = os.path.join(bernoulli_dir, 'bernoulli.stan')
data_file = os.path.join(bernoulli_dir, '')
# instantiate, compile bernoulli model
model = CmdStanModel(stan_file=stan_file)
# run CmdStan's variational inference method, returns object `CmdStanVB`
vi = model.variational(data=data_file) #this is error step

OS: win10
cmdstan: 2.3.0

For some reason, the CmdStan JSON parser failed. @WardBrian or @rok_cesnovar ?

@voyager, could you please check the CmdStan version - did you mean 2.30.0?

Running with show_console=True might give more information