Solution
1. Ensure that NI Application Web Server is running in Windows Services.
Start Menu >> Services >> Find NI Application Web Server. Start it if it is not already running and see if the issue is resolved.

2. Check if another application is running on the LabVIEW Web Server port.
- Navigate in a web browser to http://localhost:3582, or launch web server configuration from LabVIEW >> Tools >> Options >> Web Server >> Configure Web Application Server.
- Go to Web Server Configuration.
- You will be able to see from the lower box which port Application Web Server is running on.
- Launch command prompt (Start Menu >> Type cmd >> Press Enter).
- Use command netstat -o -n -a | findstr 0.0:8080 where 8080 is the Application Web Server port. This command will return TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING <XXXX> where <XXXX> is a process identifier (PID) number.
- Use Task Manager to find what process this is. It should be ApplicationWebServer.exe. See Additional Information for more detailed instructions for different Windows operating systems.
3. If a different application is running on the same port LabVIEW Web Server is supposed to run, close this application and see if the issue is resolved. If you are unable to move this application to a different port, proceed to step 4.
4. Configure Web Server to use a different port. Then, you will use the following syntax to address the LabVIEW web server:
http://localhost:XXXX where
localhost can be replaced with either server name or IP address, and
XXXX is replaced with the port you have chosen to use for LabVIEW web server.
5. If the following steps do not resolve the issue, check the web server error logs for further insight. These can be found at
C:\Program Files (x86)\National Instruments\LabVIEW 20XX\resource\webserver\logs\error.log where
20XX is replaced with the version of LabVIEW being used. Note that for 64-bit LabVIEW,
Program Files (x86) would be replaced with
Program Files.