LabVIEW Real-Time Version Mismatch When Connecting to NI Real-Time Target

Updated Feb 15, 2024

Reported In


  • CompactRIO Controller
  • PXI Controller
  • Controller for Compact FieldPoint


  • LabVIEW Real-Time Module
  • LabVIEW
  • LabVIEW Real-Time Module
  • Measurement & Automation Explorer (MAX)

Operating System

  • PharLap
  • Linux
  • NI Linux Real-Time

Issue Details

When I attempt to connect to my Real-Time (RT) controller from my LabVIEW project or deploy code, I get the following error: 

Access Denied: LabVIEW RT communication protocol version mismatch.


Access denied: This target is running a version of LabVIEW Real-Time that is different than the Real-Time Module software on the host computer.  You can verify the version and reinstall the Real-Time software using Measurement & Automation Explorer.
How can I fix this?


This error occurs when the host machine has a different version of the LabVIEW Real-Time Module installed than the one on the target controller. To resolve this error, install the same version of the LabVIEW Real-Time Module on the controller as the version of the LabVIEW Real-Time on the host.

  1. Verify the LabVIEW version used in the host. This can be checked as follows:
  1. Verify the LabVIEW version installed in the RT controller. Open NI MAX, expand the Software tab of the controller under Remote Systems, and note the LabVIEW Real-Time version that exists on the target. The error message occurs if these versions are different (2023Q1 image above vs 22.3 image below). 
  1. Depending on the RT image (Linux Base or legacy) version installed on the RT controller, the process to change the LabVIEW Real-Time version will be different.
Linux Base Image version equal to or newer than the LabVIEW version installed on the host PC
For instance, LabVIEW 2023 is used in the host, and the Linux Base Image version on the controller is 2024Q1.
  1. Modify the LabVIEW version by right-clicking the Software tab and selecting Add/Remove Software.
Linux Base Image version older than the LabVIEW version installed on the host PC
For instance, LabVIEW 2023 is used in the host, and the Linux Base Image version on the controller is 2022Q3.
  1. Update the Linux Base image on the controller to the same version in the host or newer. Additional details on this process can be found in this article.
  2. Select the programming environment that matches the host PC, in this example LabVIEW 2023.
Legacy Installation
If there is a legacy installation on the RT controller instead of a Linux Base image, reformat your controller and install the same version of LabVIEW Real-Time on the target that is on the host. The image below shows what the Software tab looks like for a legacy installation and also the window you will see after selecting Add/Remove Software. Depending on the software installed on the host PC, you might see any of the 2 options.

Additional Information

When installing software to your Real-Time target, the LabVIEW Real-Time Software Wizard should default to use the latest versions of software available on the host PC.