Googlebot keeps throwing MethodNotAllowed errors in Application#index

Hi guys,

Does anyone know how to solve this problem? As long as my app has
lived, Googlebot (IP 66.249.68.199) brings up the
ActionController::MethodNotAllowed error several times a week, saying
“Only put requests are allowed.” How is Googlebot even accessing
Application#index, and why are only post requests allowed? Thanks.