I'm facing this error when upgrading from 4.2.x to 4.3.x: "No module named ConfigParser" or "No module named StringIO"

Example error when trying to start services:

Summary:

The upgrade from Arcadia 4.2 to 4.3 includes a change in the versions of python supported to run the Arcadia Visualization Server (changed from 2.6 to 3.6). As a result, you may have some custom settings that reference version of libraries that changed after python3 in your Arcviz Settings (if using Ambari/HDP) or your Arcadia Visualization Server Safety Valve (settings_cm.py) if you’re using Cloudera Manager:

import sys
import os
import glob
import socket
import subprocess
import ConfigParser
import StringIO

from settings import *

To fix the issue you need to update the library references to be python3 compliant:

import sys
import os
import glob
import socket
import subprocess
from configparser import ConfigParser
from io import StringIO

from settings import *

After making that update, and restarting the Arcadia Visualization Server, you should be able to access the Arcadia UI like normal.