Unable to Start License Server When Using NI VLM

Updated Jul 28, 2023

Reported In


  • Volume License Manager

Issue Details

When I try to start my NI Volume License Manager (VLM), I get the error Unable to Start License Server. 

I hit the "Apply Changes" button in VLM after installing a license file, but now I am unable to start my license server. 


There are multiple problems that can cause the Unable to Start License Server error and the license server to be unable to start. 

Open the error log lmgrd.log as specified in Enabling and Locating Volume License Manager Debug Log to see if there are any error messages as to why License Manager was unable to start.

Common causes and troubleshooting steps include:
  • Restart Required - In order for the services to run properly, you must restart your computer after installing NI VLM. Make sure you have done this since installing.
  • Port Already in Use - There could be another program on your computer using the same port that NI VLM is trying to use by default, causing NI VLM to not be able to start. This is especially likely if there are other software on your computer that use FlexLM (lmgrd.exe) or LMTools to manage their licenses, and if you find the error Failed to open TCP-port in lmgrd.log at the time when you attempted to start VLM.

    Open a command prompt with Administrator privileges, and use the command netstat -b to see if the NI VLM default port 27000 is currently being used by a different program. Other software such as TCPView can also be used to check which program is using what port if none are shown with netstat.

    If another program is using the same port as Volume License Server's lmgrd.exe, you can change the port that NI VLM uses by following the instructions in Configuring Communication Ports for NI VLM or FLEXnet Publisher . However, once the port is changed in Volume License Manager, you will need to correspondingly change the ports set in the clients as well. If no ports are specified, the default port 27000 is being used.
  • Refresh License File - It is possible that NI VLM is unable to load the license file properly, and thus is unable to serve licenses over your network. Try first refreshing NI VLM by stopping and then restarting the server. If that doesn't solve the problem, try reinstalling the license file by going to File»Install Agreement License File. Note: Verify the license file received was for VLM and not any other License Manager.
  • Reinstalling -  Reinstalling or running a repair on NI VLM can resolve this issue, particularly if netstat already shows that VLM's current port is not in use. Symptoms that point to this solution may include the associated service not being able to stay started in the Windows Services list. In the event the NI License Manager service was removed from your systems LMTOOLS, you must repair or reinstall NI VLM to resolve the license server error in VLM. This can be done using NI Package Manager. 
  • Migrating and Upgrading - This error can occur when you try to import a backup from an older version of VLM. It is best practice to migrate to the same version and then upgrade one version at a time. Reinstalling the license file and then starting the server can fix this issue. 

Additional Information

If the software using port 27000 is also lmgrd.exe, and this persists even after rebooting your computer, it is likely that another software is also using FlexLM to manage their licenses. Search your computer for other instances of lmgrd.exe and check the path of the program to see which software could be causing the conflict