Volume License Manager (VLM) Fails to Launch with Unknown Error

Updated May 9, 2023

Reported In


  • Volume License Manager

Issue Details

Every time I try to open NI Volume License Manager I receive an error message stating:

An unknown error has occurred. Contact National Instruments for technical support at ni.com/support


Typically, this error indicates corruption in one of the configuration files. This may happen if the server is powered off unexpectedly, especially if it is hosted on a virtual machine.

There may be several ways to fix this issue:


  • Restart the NI License Server service.
  1. Click Start» Control Panel» System and Security» Administrative tools» Services.  
  2. Locate NI License Server.
  3. Right-click and select Stop.
  4. Right-click again and select Start

This should reset the VLM data and remove any kind of corruption, so the next time that you launch Volume License Manager the NI VLM Getting Started Wizard will appear. 

Note: This process will remove your current VLM configuration (license file, user/computer information, client permission, etc.) In order to pull your previous VLM configuration, follow the steps to restore VLM with a backup file: Restoring NI VLM from a Backup File

Additional Information

If none of the below-mentioned steps worked, please consider force reinstalling the NI VLM on your computer.