I got this error today in GitLab FOSS/CE running in docker compose when testing a webhook.
This solution helped me, specifically removing the
hostname: from the compose config.
version: '3.6' services: web: image: 'gitlab/gitlab-ce:latest' restart: unless-stopped # hostname: 'git.quinncasey.com' environment: ...
This might break things cascading down from this one config option, but time will tell.