Raise KeyError("Unknown variable %s" % var), KeyError: "Unknown variable

Description of your problem

The result add a new parameter “sigma_obs_log_”, and get a error:
raise KeyError(“Unknown variable %s” % var), KeyError: "Unknown variable…

how do I make the result without “sigma_obs_log_”? Thank you.
The type of pm.fit is ‘pymc3.backends.base.MultiTrace’, need I add other code to get final result with dict type? Thank you.
####my code:
y_obj = pm.Normal(“model_like”, mu=Y_new, sd=sigma_obs, observed=object_y) # normal(Y, sigma_obs)
trace_pars = pm.fit(method=‘advi’,obj_optimizer = pm.adagrad_window,n = iter_num).sample(500)

Sorry but I don’t really understand your code. How did you define sigma_obs? Could you expand your code to get a minimum, self contained example that produces the error you saw?