[Answer]-Image2 django-ckeditor plugin: configure url

Doing some research about the django-ckeditor configuration, it seems that with some recent update the CKEDITOR_UPLOAD_PATH has passed from absolute to relative https://github.com/shaunsephton/django-ckeditor#id2

So just changing:

CKEDITOR_UPLOAD_PATH = os.path.join(MEDIA_ROOT, 'ck_uploads')

by:

CKEDITOR_UPLOAD_PATH = 'ck_uploads/'

Solved my problem