AttributeError: 'str' object has no attribute 'regex' django 1.9

Question

I am working with django 1.9 and I am currently coding - in Windows Command Prompt - python manage.py makemigrations and the error:

AttributeErr

Answer 1

Also make sure to remove the beginning empty url pattern--can be overlooked when migrating your urls.

urlpatterns = ['', # <== this blank element ('') produces the error.
    ...
]

tl;dr

For the curious, I found this out by adding a warning to the check_pattern_startswith_slash method in the django.core.checks.urls module:

def check_pattern_startswith_slash(pattern):
    """
    Check that the pattern does not begin with a forward slash.
    """
    if not hasattr(pattern, 'regex'):
        warning = Warning(
            "Invalid pattern '%s'" % pattern,
            id="urls.W002",
        )
        return [warning]

And, sure enough, I got a bunch of warnings like this:

?: (urls.W002) Invalid pattern ''