Cloud Endpoints portal 500 internal server error

Hi

Few days ago all of our Endpoints services gets 500 internal server error no matter on all APIs , when using the Endpoints portal.
when simualting the request directly to the endpoints or to the backend itself it works.

is there any known issues on the Endpoints portal that can cause this?
any chance it got something related to the letsencrypt certificate chagne on 30-9? maybe the Google frontend that tries to reach the endpoints does it with old verification?

there is nothing on the logs as we dont even seems to reach to the endpoints, the portal just shows 500 internal server error and thats it.

10x