This command will directly show you the name of the application (e.g., node , python , docker ) and its PID. Step 2: Terminate the Conflicting Process
Open Terminal and type lsof -i :11501 .If you see no output, the software intended to run on that port isn't started. 2. Firewall Restrictions localhost-11501
Add an explicit inbound/outbound rule in Windows Defender Firewall or Linux iptables / ufw to allow traffic on port 11501. Step 4: Verify Hosts File Mapping This command will directly show you the name
: Double-check that you haven't typed a different port (like 8080 or 11500) by mistake. Your operating system may be resolving localhost to
This is a subtle but very common issue. Your operating system may be resolving localhost to the IPv6 loopback address ::1 while your server is configured to listen only on the IPv4 loopback address 127.0.0.1 .