Missing required parameter: code_verifier

​@Omnika25034 - What “kind of app” do you have selected in your OAuth settings? Web or native?

If the type is “native” (client side app), you’ll need to generate a code challenge query parameter in the oauth url.

See example here:

https://github.com/tcampb/calendly-webhooks-ui/blob/fa9f5a0949ae5129836d4eff3681068b4a31b403/src/components/Login.jsx#L18

Hey thank you for your reply.

The type os set to Web.

​@Omnika25034 - are you able to share the code examples you are using to generate the oauth url and request the auth token (with client credentials hidden)?

As much as I’d like to, this error is thrown only specifially when I configure app-acc.example.com as redirect URI in the Calendly app settings. Of course I have made sure this is the same url set on my server. I’m just dumbfounded that no issues arise when I use localhost (Sandbox env) or when I use app.example.com (Production). As soon as I configure app-acc.example.com the OAuth flow doesn’t succeed and I am left with the error: Missing required parameter: code_verifier.

Why does this specifically happen for the app-acc subdomain? 

What content type are you sending the request as, json or url encoded? Im wondering if the “-“ in your redirect url is not being properly encoded.  

Thank you for your reply.

I’m using Python in the backend and the httpx library to make the request. The required parameters are set in the data argument when making a post request, so it’s an application/x-www-form-urlencoded request. 

Thanks for the additional details. Executing the Python code below with your redirect URI worked as expected; I was unable to reproduce the error. I would recommend creating a brand new app in the developer portal for the redirect uri that includes a “-”. If that doesn’t work, then I would reach out to support+developer@calendly.com with this information. They’ll be able to look at the logs to better understand why the request is failing.

----------

import httpx

url = "https://auth.calendly.com/oauth/token"

data = {"code": "CODE", "grant_type": "authorization_code", "redirect_uri": "https://app-acc.example.com"}

auth = httpx.BasicAuth("CLIENT_ID", "CLIENT_SECRET")

response = httpx.post(url, data=data, auth=auth)

print(response.status_code)

print(response.json())