NoReverseMatch at / ' homepage' is not a registered namespace

I am building my django app from bas.html and with child themes

and get these errors:

any help woud be appreciated.

Tim

NoReverseMatch at /

' homepage' is not a registered namespace

Request Method:	GET
Request URL:	http://localhost:8000/
Django Version:	2.0.6
Exception Type:	NoReverseMatch
Exception Value:	' homepage' is not a registered namespace
Exception Location:	/Users/timvogt/newdjango/lib/python3.6/site-packages/django/urls/base.py in reverse, line 86
Python Executable:	/Users/timvogt/newdjango/bin/python3
Python Version:	3.6.5
Python Path:	['/Users/timvogt/coolapp', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python36.zip', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6', '/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/lib-dynload', '/Users/timvogt/newdjango/lib/python3.6/site-packages']
Server time:	Mon, 25 Jun 2018 20:46:07 +0000

Error during template rendering

In template /Users/timvogt/coolapp/homepage/templates/homepage/base.html, error at line 2

' homepage' is not a registered namespace

1	<p>
2	<a href='{% url ' homepage:index ' %}'>main</a>
3	<a href='{% url ' homepage:topics ' %}'>topics</a> {% block content %} {% endblock content %}

vieuws.py

from django.shortcuts import render

from .models import Topic

def index(request):

"""the homepage for the homepage"""

return render(request, 'homepage/index.html')

def topics(request):

"""show all topics"""

topics = Topic.objects.order_by('date_added')

context = {'topics': topics}

return render(request, 'homepage/topics.html', context)

# Create your views here.

base.html

<p>

<a href='{% url ' homepage:index ' %}'>main</a>

<a href='{% url ' homepage:topics ' %}'>topics</a> {% block content %} {% endblock content %}