GitHub authentication doesn't work anymore

[marcelotto]

When I tried to authorize myself via GitHub to submit a post, I was initially successfully redirected to the corresponding page at GitHub to authorize the app. When redirected back, however, I ended up with an "Internal Server Error (500)". After a page reload, this error message then appears:

Failed to authenticate: %Ueberauth.Failure{errors: [%Ueberauth.Failure.Error{message: "The code passed is incorrect or expired.", message_key: "bad_verification_code"}], provider: :github, strategy: Ueberauth.Strategy.Github}