ebay changing Certification Authority - using Finding API

[DancingGuy]

I am trying to comply with an ebay notice to developers to test endpoints in the sandbox to get ready for the switch in Certification Authority in January.

My python ebaysdk version is 1.13.0. My python version 3.8.5

When I follow the instructions to use svcs,sandbox.ebay.com with my sandbox appid, I get the following error:

Python exception:
InvalidHeader: Value for header {X-EBAY-SOA-SECURITY-APPNAME: None} must be of type str or bytes, not <class 'NoneType'>

response = api.execute('findItemsByCategory', request)

api: <ebaysdk.finding.Connection object>
request: {'categoryId': 260, 'itemFilter': {'name': 'S...}  | len(request): 5

Exception raised on line 949 of file 'PYTHON:\site-packages\requests-2.24.0-py3.8.egg\requests\utils.py'.

   947:             raise InvalidHeader("Invalid return character or leading space in header: %s" % name)
   948:     except TypeError:
-->949:         raise InvalidHeader("Value for header {%s: %s} must be of type str or "

global InvalidHeader: <class 'requests.exceptions.InvalidHeader'>

My exact same script with this call in production mode yaml file works as normal.

api = Connection(config_file='C:\Users\eBay_Sandbox\Documents\Finding\ebay.yaml', siteid="EBAY-US")

I'm confused as to what I need to change in my ebay.yaml or api call to test and confirm.

Thanks for any advice.