Changing location of sqlite database on rpi running django

I am running a django project on a raspberry pi and want to move the database to an external hard drive that is connected. my settings looks like this:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': '/mnt/MOCStorage/database.db,
    }
}

When I run manage.py migrate, I get this error:

django.db.utils.OperationalError: unable to open database file

I have mounted the drive to /mnt/MOCStorage and used chmod to change the permissions of /mnt and /mnt/MOCStorage to 775.

How can I get this database to work here?