I believe that AWS themselves no longer allow you to create new CodeCommit repos, since they are in the process of closing the service down. You can read about this here on the AWS blog. The message you’re getting is a bit unclear, but the short of it is that if you already have a CodeCommit repo, they encourage you to migrate out of it to another git provider (such as GitHub, as an example), but they are not allowing you to create new ones.