Django報如下錯誤：
RuntimeError at /login
You called this URL via POST, but the URL doesn't end in a slash and you have APPEND_SLASH set. Django can't redirect to the slash URL while maintaining POST data. Change your form to point to 127.0.0.1:8000/login/ (note the trailing slash), or set APPEND_SLASH=False in your Django settings.
You're seeing this error because you have DEBUG = True in your Django settings file. Change that to False, and Django will display a standard page generated by the handler for this status code.
解決：
檢查URL的列表裏，和html文件裏的action是否一致：後面有/就必須都有，否則要麼就都沒有。
原因：Django有個特殊的功能，會自己在url後面加上/（沒有的時候）。