Based on your clarifying comments, it appears your browser is accessing a previous version of your app server.
I have run into this problem myself when using the PyCharm IDE. On Windows, the way to shut down these old versions of the server is to press either Ctrl+Alt+Delete
or Ctrl+Shift+Esc
(Windows 10) to view your list of running processes. Then scroll down until you see processes named Python
and shut them all down.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…