Unable to access GitHub repository - Error 404/422

404 - Not Found

You may see the following error whilst connecting to your GitHub repository using the oAuth method.

GET https://api.github.com/repos/org-slug/repo-slug/keys?per_page=100: 404 - Not Found // See: https://docs.github.com/rest/reference/repos#list-deploy-keys

This error usually means the user you're connected as, does not have admin access to the repository you're trying to add. Further details on permissions can be found here.

422 - Validation Failed

Alternatively, if you see the following error:

POST https://api.github.com/repos/org-slug/repo-slug/keys: 422 - Validation Failed
Error summary:
  resource: PublicKey
  code: custom
  field: key
  message: key is already in use // See: https://docs.github.com/rest/reference/repos#create-a-deploy-key

This would mean your project's public key, already exists within the repository.

And the following would mean the project's webhook already exists in the repository:

 POST https://api.github.com/repos/org-slug/repo-slug/hooks: 422 - Validation Failed
Error summary:
  resource: Hook
  code: custom
  message: Hook already exists on this repository // See: https://docs.github.com/rest/reference/repos#create-a-repository-webhook

You could manually remove this and try adding the repository again, or alternatively, you could add the repository manually.