I wanted to authenticate a user with OAuth the directions here.
Step 1 is to redirect users to the following URL to request their GitHub identity: http://github.com/login/oauth/authorize. The
client_id param is required here and the docs describe the
client_id as: The client ID you received from GitHub for your GitHub App.
I mistakenly put the 4-digit
APP_ID as the
client_id and I was redirected to GitHub’s 404 Page Not Found page. After shamefully long debugging I realized that the
client_id is actually Client ID that is in the OAuth credentials section of the Basic Information for the GitHub Apps page not the 4-digit
APP_ID. After fixing this my redirect worked great
Hopefully this post can help other people that may make the same mistake!