I had this issue because Python couldn’t find my config file, though you would never know it by the error message. Apparently it does not look for the config file relative to the file in which the code is running, but rather relative to the current working directory (which you can get from os.getcwd()). I used the following code to initialize the logger. The log.config file is in the same directory as the file running this code:
from os import path
log_file_path = path.join(path.dirname(path.abspath(__file__)), 'log.config')
logging.config.fileConfig(log_file_path)