Look at the differences, you are using Absinthe.Plug.GraphiQL
instead of Absinthe.Plug
scope "/api" do
pipe_through :api
forward "/", Absinthe.Plug,
schema: AppWeb.Schema
end
scope "/graphiql" do
pipe_through :api
forward "/", Absinthe.Plug.GraphiQL,
schema: AppWeb.Schema
end