What is running on your PC?
: Samsung changed server protocols, or your firewall blocked the connection.
If you need a specific older version of Android, you can input the PDA, CSC, and Phone strings manually. Samfirm Tool V3.3
Look for the box; it should turn blue or light up, indicating your phone is properly connected.
Samfirm Tool V3.3 is a lightweight, Windows-based executable developed by a recognized XDA Developers forum member. Its sole purpose is to decrypt and download official Samsung firmware directly from Samsung’s own secure update servers (FUS – Firmware Update Server). What is running on your PC
Pause and resume the download, or check your internet firewall settings to ensure Samfirm is not being blocked from accessing port 443 or 80.
Before downloading, ensure your computer meets these basic requirements: Look for the box; it should turn blue
For users seeking additional options, several alternatives exist: