“None”不是可调用路径或dotnotation路径

Question

我在Ubuntu14.04上使用django1.9.4和python3.4.3来构建一个博客，但是我得到了以下错误。我不知道我是怎么做到的，只是没用。在

ViewDoesNotExist at /
'None' is not a callable or a dot-notation path
Request Method: GET
Request URL:    http://127.0.0.1:8000/
Django Version: 1.9.4
Exception Type: ViewDoesNotExist
Exception Value:    
'None' is not a callable or a dot-notation path
Exception Location: /usr/local/lib/python3.4/dist-packages/django/core/urlresolvers.py in get_callable, line 102
Python Executable:  /usr/bin/python3.4
Python Version: 3.4.3
Python Path:    
['/home/gaoliang/Desktop/my_blog',
 '/usr/local/lib/python3.4/dist-packages/setuptools-18.1-py3.4.egg',
 '/usr/local/lib/python3.4/dist-packages/stevedore-1.12.0-py3.4.egg',
 '/usr/local/lib/python3.4/dist-packages/six-1.10.0-py3.4.egg',
 '/usr/local/lib/python3.4/dist-packages/pbr-1.8.1-py3.4.egg',
 '/home/gaoliang/Desktop/my_blog',
 '/usr/lib/python3.4',
 '/usr/lib/python3.4/plat-x86_64-linux-gnu',
 '/usr/lib/python3.4/lib-dynload',
 '/usr/local/lib/python3.4/dist-packages',
 '/usr/lib/python3/dist-packages']
Server time:    Sat, 16 Apr 2016 20:31:57 +0800

我不知道为什么django指出我在html中有一个错误。在

^{pr2}$

你能帮帮我吗？在