AWS-CLI throws unexpected "Session" error in Python

I have been using AWS CLI on Ubuntu for a month now. But today AWS CLI is throwing python error, I haven't seen before:

sashank@sashank:~$ aws configure
Traceback (most recent call last):
  File "/usr/local/bin/aws", line 27, in <module>
    sys.exit(main())
  File "/usr/local/bin/aws", line 23, in main
    return awscli.clidriver.main()
  File "/usr/local/lib/python2.7/dist-packages/awscli/clidriver.py", line 48, in main
    return driver.main()
  File "/usr/local/lib/python2.7/dist-packages/awscli/clidriver.py", line 173, in main
    parser = self._create_parser()
  File "/usr/local/lib/python2.7/dist-packages/awscli/clidriver.py", line 154, in _create_parser
    command_table['help'] = self.create_help_command()
  File "/usr/local/lib/python2.7/dist-packages/awscli/clidriver.py", line 149, in create_help_command
    cli_data.get('help_usage', None))
  File "/usr/local/lib/python2.7/dist-packages/awscli/help.py", line 259, in __init__
    HelpCommand.__init__(self, session, session.provider,
AttributeError: 'Session' object has no attribute 'provider'

      

        
        
        
      

    

I tried to clean AWS CLI and delete all package files and reinstall but the error persists. Plz help !! Thank.