GitLab: Unable to fork my own project

1. From the top, blue navigation menu, go to Groups > Your Groups,
2. Click the New group button on the top right corner,
3. Type in the details of your new group,
4. Click the Create group button.

On the Members page of your new group, manage your members. Your account would probably already be added.

Now you can fork that project.

Well, seems like you have to create a group in order to do that

From https://gitlab.com/gitlab-org/gitlab-ce/issues/25805:

For anyone running into this question: What I did is first fork a repository to another name space (group or other), then rename the project and also the repository in the Advanced Settings. Then transfer the project back to the original namespace (group).