werkzeug.exceptions.BadRequestKeyError

[Williamrjw]

werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand.
KeyError: 'code'

Traceback (most recent call last)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\flask\app.py", line 2088, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\flask\app.py", line 2073, in wsgi_app
response = self.handle_exception(e)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\flask\app.py", line 2070, in wsgi_app
response = self.full_dispatch_request()
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\flask\app.py", line 1515, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\flask\app.py", line 1513, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\flask\app.py", line 1499, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)Open an interactive python shell in this frame
File "D:\git\onenote_export\onenote_export.py", line 232, in main_logic
code = flask.request.args['code']
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\werkzeug\datastructures.py", line 377, in __getitem__
raise exceptions.BadRequestKeyError(key)
werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand.
KeyError: 'code'

I am a beginner in Azure.
What should I do?
Thank you for your answer!