Jira issue originally created by user margus:
I used above code to test annotations without namespaces just to find out that there there is missing \ (or 2 if you count escaping) at the end of that string.
This works: $reader->setDefaultAnnotationNamespace('Doctrine\Common\Annotations\');
reference guide where I found error is here: http://www.doctrine-project.org/projects/common/2.0/docs/reference/annotations/en#setup-and-configuration:default-namespace
Comment created by @guilhermeblanco:
Already fixed on documentation.
Issue was closed with resolution "Invalid"