Error 404 Page Cannot Be Found When Using Remote Front Panels and Web Services

Updated Jul 27, 2021

Reported In

Software

  • LabVIEW

Issue Details

https://www.ni.com/en-us/support/downloads/drivers/download.ni-usblan-driver.html#336071 When using remote front panels or Web Services in LabVIEW, I am unable to access the web page or HTTP Method. Instead, the page does not load and I see an error message(s) similar to the following.

HTTP 404 - File not found
The page cannot be found
Internet Explorer cannot display the webpage
The connection has timed out

Solution

There are multiple possible causes for this error. The sections below address the most common way that this can be resolved.


Enable from LabVIEW and Check Settings


Check LabVIEW Run-Time Engine Versions

  • The client needs to have the same LabVIEW Run-Time Engine version as the server. You can check the version installed in Measurement & Automation Explorer (MAX) under My System » Software in the Configuration Tree (left side).


Check URL

  • Check the extension of the published web page. In LabVIEW 7.1 and prior, web pages were published with the extension .htm. In LabVIEW 8.0 and later, web pages have the extension .html.
  • See if the webpage can be viewed on the same machine running the server. If the server machine also cannot access the webpage, try creating the remote front panel again using the Web Publishing Tool. Note the URL generated and check for errors. Also try using Preview in Browser.
  • If the server can see the web page, check if all clients are having a problem viewing the web page or just one client. This will help narrow down if the problem is on the server or client side. If all clients are having problems, then the server or network settings are the most likely culprits. If only one client is having a problem, than that specific client is the most likely culprit.


Check Connections and Port Usage

  • See if the client can ping the server. Open command prompt by navigating to Start » Run and entering cmd in the Open line. Type ping XXX.XXX.XXX, where XXX.XXX.XXX is the server IP address. Then press Enter.
  • When using a USB connection with RT targets (i.e. cRIO), make sure the NI-USBLAN Driver is installed in the PC where you are trying to access the Remote Panel Server/ Web Service. The driver emulates the USB connection as an Ethernet device, and an automatic DHCP network is created over the USB device port. If the driver is not installed the IP 172.22.11.2 address will not be recognized.
    • Note: You can check if the NI-USBLAN driver is installed by going to the Installed tab on NI Package Manager. 
  • Ensure that there are no port conflicts. For example, if the Remote Panel Server and System or Application Web Servers are set to run on the same port, one or the other will not have proper access. A port conflict can be resolved by changing port settings.
 Default PortChange Port Setting From
LabVIEW Remote Panel Server8000LabVIEW >> Tools >> Options >> Web Server >> Remote Panel Server
LabVIEW Web Server8080Web Server Configuration. See LabVIEW Web Server Not Working Despite Being Enabled.
 

Additional Information

The page cannot be found message indicates that the client cannot find the published web page. There are numerous potential root causes, and the above list is by no means exhaustive.