QGIS Python - Error: Algorithm not found

Question

Trying using the processing toolbox in a standalone python script the needed Algorithm could not be found:

Error: Algorithm not found 
Error in sys.excepthook:
Traceback (most recent call last):
 File "/Applications/QGIS.app/Contents/Resources/python/qgis/utils.py", line 196, in qgis_excepthook
 showException(type, value, tb, None, messagebar=True)
 File "/Applications/QGIS.app/Contents/Resources/python/qgis/utils.py", line 107, in showException
 open_stack_dialog(type, value, tb, msg)
 File "/Applications/QGIS.app/Contents/Resources/python/qgis/utils.py", line 142, in open_stack_dialog
 iface.messageBar().popWidget()
AttributeError: 'NoneType' object has no attribute 'messageBar' 
Original exception was:
Traceback (most recent call last):
 File "test_standalone_copy.py", line 33, in <module>
 outputs_QGISINTERSECTION_1=processing.runalg('qgis:intersection', outputs_QGISFIELDCALCULATOR_1['OUTPUT_LAYER'],polygon,False,None)
TypeError: 'NoneType' object has no attribute '__getitem__'

I tried already the solution in Error: Algorithm not found (QGIS) but unfortunately it didn't worked...

This is my script

import sys
sys.path.append('/Applications/QGIS.app/Contents/Resources/python')
sys.path.append('/Applications/QGIS.app/Contents/Resources/python/plugins')
sys.path.append('/Applications/QGIS.app/Contents/Resources/python/plugins/processing') 
import qgis
from qgis.core import * 
import json, requests
import processing 
# supply path to qgis install location
QgsApplication.setPrefixPath(r"/Applications/QGIS.app/Contents/MacOS", False)
# create a reference to the QgsApplication, setting the # second argument to False disables the GUI
qgs = QgsApplication([], False)
# load providers
qgs.initQgis() 
# test set of coordinates
geometry_decode = [(-0.125037,51.5307), (-0.12763,51.5338), (-0.128062,51.5344), (-0.128236,51.5346), (-0.128305,51.5347), (-0.128377,51.5348), (-0.128438,51.5349)]
geometry = [QgsPoint(point[1],point[0]) for point in geometry_decode] 
line = QgsGeometry.fromPolyline(geometry) 
route = QgsVectorLayer("LineString?crs=epsg:4326&index=yes","route","memory")
pr = route.dataProvider() 
route.startEditing() 
feature = QgsFeature()
feature.setGeometry(line) 
route.addFeatures([feature])
route.commitChanges()
QgsMapLayerRegistry.instance().addMapLayer(route) 
filepath_polygon ='ne_50m_admin_0_sovereignty.shp'
polygon = QgsVectorLayer(filepath_polygon,"countries","ogr") 
outputs_QGISFIELDCALCULATOR_1=processing.runalg('qgis:fieldcalculator',route,'tot_length',0,10.0,3.0,True,'$length',None)
outputs_QGISINTERSECTION_1=processing.runalg('qgis:intersection', outputs_QGISFIELDCALCULATOR_1['OUTPUT_LAYER'],polygon,False,None) 
# Write your code here to load some layers, use processing algorithms, etc.
# When your script is complete, call exitQgis() to remove the provider and # layer registries from memory
qgs.exitQgis()

• Joseph: Which QGIS version are you using?
• CanadaRunner: Version 2.18.15 - Vienna