With this error message Gerrit rejects to push a commit to a project which is configured to always require a Change-Id in the commit message if the commit message of the pushed commit does not contain a subject and a message, but only a Change-Id.

This error happens if the Change-Id is the only line in the commit message.

You can see the commit messages for existing commits in the history by doing a git log.

Change-Id is the only line in the commit message

Gerrit does not parse the subject of a commit message for the Change-Id even if this is the only and last paragraph of the commit message.

If the Change-Id is the only line in the commit message you must update the commit message and insert a subject as the first line in the commit message. The Change-Id must be in the last paragraph of the commit message, i.e. separated from the subject by a blank line. How to update the commit message is explained here.

Part of Gerrit Error Messages