The new 7.7.0 and 7.7.1 releases of GitLab Community Edition use a new settings panel in the administration interface for GitLab. This page replaces the gitlab.rb or gitlab.yml configuration files, which makes it really easy to change settings.
However, this release also enables user signups by default in said administration panel (not the default in previous versions). Some administrators might not want this functionality, especially if their server contains internal projects for a company. If you did not have a configuration setting in gitlab.rb or gitlab.yml explicitly disabling user signups, the new releases will enable them.
Administrators are advised to confirm that their intended configuration remains intact when updating to the newest GitLab versions.