I found the cause and solution ✅

This issue wasn’t caused by Django or Python but by a Windows 11 update (October 2024 patches KB5066835 and KB5065789) that broke localhost connections using HTTP/2.

To fix it:

1. Open the Registry Editor (regedit).

2. Navigate to:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters
   
   

3. Add these DWORD (32-bit) values:

   EnableHttp2Tls = 0
   EnableHttp2Cleartext = 0
   
   

4. Restart your computer.

After restarting, Django’s development server and Live Server both worked again at http://127.0.0.1:8000.

This should help others who get “The connection was reset” or “127.0.0.1 refused to connect” after recent Windows updates