KeyError: 'weighted_metrics' on rasa_core.run

[antonioiba]

Rasa Core version:
rasa_core==0.11.8

Python version:
Python 3.6.6 :: Anaconda, Inc.

Operating system (windows, osx, ...):
Windows 7

Issue:
When I run the Rasa Core with the followin command:
python -m rasa_core.run --enable_api --endpoints endpoints.yml -d models/dialogue -u models/nlu/default/currentv5 -o logs/rasa_core.log

The following error appears:

training_config['weighted_metrics'])
KeyError: 'weighted_metrics'

Is similar to #1109

I try with TensorFlow 1.10.0 and 1.11.0

I followed the instruction in Rasa Core migration from v0.10.x
In v0.10.x is working.