diff --git a/python/fbprophet/forecaster.py b/python/fbprophet/forecaster.py
index 973728c..1cc6144 100644
--- a/python/fbprophet/forecaster.py
+++ b/python/fbprophet/forecaster.py
@@ -1119,6 +1119,7 @@ class Prophet(object):
                 params = model.optimizing(**args)
             except RuntimeError:
                 # Fall back on Newton
+                logger.warning('Default optimization returns with an error. Falling back to Newton method.')
                 args['algorithm'] = 'Newton'
                 params = model.optimizing(**args)