OAuth Failure on Step 1--Authorize

[Terence_Leung]

I am going to integrate the OAuth2 authentication with my existing apps.
The first step is to send a GET request to https://airtable.com/oauth2/v1/authorize .
But I failed on the first step.
Here is the error:

Spoiler

http://localhost/?error=invalid_request&error_description=%22code_challenge%22+must+be+a+valid+url-e...

Below are the parameters for the GET request:

• client_id = //not exposed here
• client_secret = //not exposed here
• redirect_uri = http://localhost/
• response_type=code
• scope=data.records:read data.records:write
• state=sadjfhkjDFHKJShk23489sldfhjksdkssdffsf // random text
• code_challenge_method=S256
• code_challenge=MTA4ZDJhYTQ1YTVhMGE3M2MwNTc3NmJiMzYyZTdhNDc3ZjgyNGUzN2U3NGZhYzA0ZGQ1NDAwYTE5OGM0OTMzYw
  // where the code verifier is SLAJFlksdlksfjljasldjflasjflasjflasfjisfjjd

I already encoded the code verifier with SHA256 and then base64 URL. So I do not know what wrong it is.
Can anyone help?

[Terence_Leung]

I found that the Code_Challenge was generated incorrectly. 
I fixed it and it is ok now