Embedded Files
Where This Error/Issue Appears?
This issue appears when the Zaperon Desktop Client fails to connect or repeatedly disconnects because the required local ports (21214–21218) are already in use or blocked by the system or network.
Users typically see the following error in desktop zaperon app:
Port conflict error.
Why This Happens?
This issue usually occurs due to one or more of the following reasons:
Another application is already using ports 21214–21218.
Local firewall is blocking inbound or outbound traffic on these ports.
Endpoint security or antivirus software is restricting local port binding.
Corporate firewall or network security tool is blocking required connections.
Previously crashed processes did not release the ports.
✔ Key Steps For Resolving This Issue
1. Identify port usage on the device
Windows:
Open Command Prompt as Administrator.
Run: netstat -ano | findstr 2121
Note the PID using the conflicting port.
macOS / Linux:
Open Terminal.
Run: lsof -i :21214-21218
Identify any application using the same ports.
2. Stop or reconfigure conflicting applications
Stop the application or service using the conflicting ports.
If the application is required, reconfigure it to use a different port range.
3. Allow ports in local firewall
Windows Firewall: Allow inbound and outbound traffic for TCP ports 21214–21218.
macOS: Allow Zaperon Client under Firewall settings.
Linux: Update iptables or ufw rules to allow the required ports.
4. Check endpoint security software
Verify antivirus or endpoint protection is not blocking Zaperon services.
Add Zaperon Client and its ports to the allowlist.
5. Restart Zaperon services
Restart the Zaperon Desktop Client:
1. In client app click on File in top ribbon.
2. Choose Exit option. this will restart the client app and all the background services.
Reboot the device if required to release locked ports.
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