Gen 1 Cloud Function (default cloudfunctions.net URL) — cannot establish an HTTPS connection to cloud function endpoint

Google Cloud Serverless Applications
1

Hi everyone,

We are experiencing an HTTPS connectivity issue with a Gen 1 Google Cloud Function.

Environment

  • Platform: Google Cloud
  • Service: Cloud Functions (Gen 1)
  • Endpoint type: Default cloudfunctions.net URL (no custom domain)
  • SSL certificate: Google-managed

Issue

A client system cannot establish an HTTPS connection to our function endpoint. They receive SSL/TLS errors such as:

Could not establish trust relationship for the SSL/TLS secure channel

They are calling the apis using a SSL certificate.

This issue started after Jan 20, There is no code/infra change from our side or at client side.

However:

  • The same endpoint works from Local developer environment
  • We see no request entries in Cloud Logging during their failed attempts.
  • No application-level errors are recorded.

This indicates the request likely never reaches the Cloud Function back-end.

  1. Is there any changes from Google side that can cause TLS handshake failures ?
  2. Are there any metrics, audit logs, or networking logs that would show rejected TLS connections to default Cloud Function endpoints?
  3. Has anyone encountered client environments failing to trust Google Trust Services certificates due to:

    • Outdated root CA store

    • TLS version < 1.2

    • SSL inspection firewall / proxy?

Any insight from others who have diagnosed similar TLS issues would be very helpful.

Thank you!