Web Publishing Tool: Cannot Preview a Web Page

Updated Jan 19, 2023

Reported In


  • LabVIEW

Operating System

  • Windows


  • LabVIEW Web Server
  • LabVIEW Remote Panel Server
  • Optional: cRIO or other real-time embedded target

Issue Details

  • I cannot preview a web page when using the Web Publishing Tool in LabVIEW.
  • I launch Web Publishing Tool and the wizard launches. I click Start Web Server and it appears grayed out and pressed. However, when I click Preview in Browser, I get a prompt saying that the web server has not been started.

You must start the LabVIEW web server before previewing your web page. Would you like to start the web server now?


This prompt appears if LabVIEW cannot detect that the web server is running. To fix this, ensure that the web server is running on an available port by following the steps below.

1. Check which port LabVIEW is using for the Remote Panel Server. The default is 8000.
  • You can check from Tools >> Options >> Web Server. Ensure that the Remote Panel Server is enabled and note the port number.

2. Use netstat command to check what application is running on this port.
  • Open the Command Prompt and by going to the Windows Start Bar and typing in "cmd".
  • Enter the following command:  netstat -o -n -a | findstr 0.0:8000 where 8000 is the port being used by Remote Panel Server.
  • This will return information with the format TCP LISTENING <XXXX> where XXXX is the process identifier (PID).  
  • Use the PID to find the application that is blocking the Remote Panel Server.
  • End this application. If this application cannot be ended, configure Remote Panel Server to use a different port.
Note: The Remote Panel Server will appear as LabVIEW.exe if running properly.

Additional Information

This behavior occurs when another application is blocking the LabVIEW Remote Panel Server port. If you are still having issues accessing your webpage, see Error 404 Page Cannot Be Found When Using Remote Front Panels and Web Services .