Volume License Manager (VLM) Troubleshooting Guide: Main Page

Ensuring the client machine can ping the volume licensing server helps verify a working network connection between them. There are two main ways to address the licensing server while performing a ping test: by machine name/alias or by IP address.

When pinging the licensing server by machine name or alias, the network relies on a domain name system (DNS) to match the name that was entered to that system's IP address. Ping tests can be performed using the Windows command line outlined below.

Running the Ping Test

For the ping test, perform a ping using both the machine name and the IP address.

1. Obtain the IP address and machine name of the Licensing Server. The IP address can be obtained using the ipconfig command and the machine name can be obtained using the hostname command from a Windows command prompt.
2. Open a Windows command prompt from the client computer and use the ping command to send a test ping to the server using its IP address.

Successful Test: 

Unsuccessful Test:

3. If the ping test was successful using the IP address, now repeat the test using the machine name instead.

What the Results Mean

Unable to Ping Licensing Server Using Its IP Address

This means that there is no network route from one machine to the other.

There is a firewall rule in Windows called "File and Printer Sharing (Echo Request)" that is usually not enabled by default. This can also affect the ability of the computers to reach each other via ping. If the firewall rules are not enabled, enable them (right-click then select Enable Rule) in Windows Defender Firewall for both Outbound and Inbound Rules:

If the ping test still fails please contact your network administrator for help to place your machines on the same network.

IP Address Responds, but the Machine Name or Alias Does Not

This is most likely a DNS issue. This will need to be resolved by either ensuring the DNS server can map the machine name to its IP address (if using a local DNS server) or avoided by addressing the licensing server using only its IP address. For help resolving DNS issues, contact your network administrator.

If Both Tests Are Successful

This confirms that the licensing server is addressable from the client machine and the network can route to the licensing server when using the machine name. Next, move on to checking to see if the correct ports are open.

The two ports used by Volume License Manager are the Licensing Port (27000 by default) and the Communication Port (4637 by default). The next step in troubleshooting is to ensure that NI License Manager (NILM) can communicate with the Volume License Server through those ports. An easy way to test this is to use Telnet.

Note:  For some versions of Windows, the Telnet client is disabled by default.  You may turn it on by navigating to Start»Control Panel»Programs»Programs and Features when your view is set to category and selecting the link to Turn Windows features on or off.  In this window check the Telnet Client box.  See the screenshot below for more information on this setting.

Testing Ports

1. Check which ports Volume License Manager is using on the license server:
   1. Go to Tools » Preferences
   2. Write down the port numbers used for the Licensing Port and Communication Port.
2. Open the Telnet client and attempt to open a connection to the two ports recorded in the previous step:
   1. Open a command prompt by going to Start Menu»Run and typing in cmd.
   2. Execute Telnet with the following syntax in the command prompt window:
      • telnet <servername> <main licensing or communication port> 
        Example: telnet ServerX 27000
   3. When the Telnet connection to the server is successful, a window will pop up with a cursor. The name of server will be in the title bar.

        d. If the Telnet connection is not successful, the error will be: Could not open connection to the host, on port <port>: Connect failed

If the telnet connection does not work, make sure that both Main Licensing and Communication ports used by VLM are open. See Getting Started with FlexNet Publisher Configuration and Unable to Communicate With License Server Error in NI VLM for more information.

3. Observe whether a connection was established.

What the Results Mean

Unable to Establish a Connection Over One or Both Ports

This means that something between the client and the volume license server is blocking the TCP communication. The most common cause is a firewall. It’s recommended to work with an IT team (if applicable) to resolve this issue.

Both Connections are Successful

The ports used by NI License Manager to communicate with Volume License Manager on the Volume License Server should be open and should allow for interaction between NI License Manager and Volume License Manager. 

Your next step in troubleshooting is to ensure NI License Manager is configured to use a licensing server and can communicate with the licensing server. This is done in the NI License Manager user interface. Once NI License Manager is configured correctly and can communicate with the licensing server, you can confirm client permissions have been added to Volume License Manager. 

Configure the Client to have the Same Domain as the License Server

An error might occur if the client computer is connected to a license server that is on a different domain than the client computer. To resolve this, add the server's domain to the client computer's DNS settings. To do this, complete the following steps on the client's computer:

To configure the DNS settings on Windows 7 and previous versions of Windows:

1. Open Local Area Network Settings from the Control Panel (Start » Control Panel » Network Connections » Local Area Connection).
2. Click the Properties button.
3. Select Internet Protocol (TCP/IP) from the list of network components.
4. Click the Properties button.
5. Click the Advanced button.
6. Change to the DNS tab.
7. Ensure Append these DNS suffixes is selected.
8. Click the Add button.
9. Enter the domain suffix of the license server and click Add.
10. Close any open dialog boxes, choosing OK and Close as necessary.

To configure the DNS Settings on Windows 10:

1. Open Network and Internet settings from the Control Panel (Start » Control Panel » Network and Internet » View Network and Status).
2. Select the Change Adapter Settings.
3. Select the Network on which you would like to verify the DNS Settings, right-click on it, and select Properties
4. Select Internet Protocol (TCP/IP) from the list of network components depending on which version of IP you are using.
5. Click the Properties button.
6. Click the Advanced button.
7. Change to the DNS tab.
8. Ensure Append these DNS suffixes are selected.
9. Click the Add button.
10. Enter the domain suffix of the license server and click Add.
11. Close any open dialog boxes, choosing OK and Close as necessary

Configuration and Connectivity

1. Add the licensing server to NI License Manager and check communication in the Network Licenses Tab. Make sure to include the port number if using ports other than 27000 and 4637, in the format of <Machine Name>:<Port Number>

Note: If NI License Manager can’t contact the license server using the machine name, try <IP address>:<Port number>.

2. If still unable to communicate with the licensing server, try editing the license file installed on the licensing server by replacing the machine name with the machine's IP address. This is only recommended as a last step.
   1. Open the license file provided by NI in a text editor and replace the machine name, found in line 1 immediately following SERVER, with the machine's IP address. The license file currently being used can be found at
      <ProgramData>\National Instruments\Volume License Manager\nivlm.lic
      Note: NI recommends creating a backup of the nivlm.lic before making any edits.
   2. Do not change any other part of the license file as this can invalidate it.
   3. Save the license file and install it in Volume License Manager. See installing license file  documentation. 

3. Once NI License Manager can communicate with the Volume License Manager, add the client permissions using Volume License Manager. If NI License Manager can’t communicate with the Volume License Manager, please review the previous steps in the VLM Troubleshooting Guide .
   1. Refer to the Adding Client Permissions Getting Started  documentation for instructions.

Interpreting the Results

NI License Manager is Unable to Contact the Licensing Server Using Either the Machine Name or IP Address

This means that NI License Manager was not able to communicate with the licensing server using the information provided in the Manage Volume License Servers dialog. This communication could be blocked by firewalls or possibly anti-virus software. If connectivity to the licensing server has not been tested already, see the Ping test and Telnet test troubleshooting guides.

If All Tests Passed, but You’re Still Encountering Issues

If the client can successfully communicate via pings as outlined in the Ping Test, can communicate over the appropriate ports as outlined in the Telnet test, and is configured correctly in NI License Manager, it’s recommended to reach out to NI support for further troubleshooting.

If All Tests are Passed, and Everything is Working Correctly

If NI License Manager can connect to the licensing server, it should be able to request a license from the licensing server. Next, the licensing server needs to be configured to provide a license to the client in question.

This article is intended for Software Administrators to assist end users in troubleshooting licensing issues. After confirming that NI License Manager (NILM) and Volume License Manager (VLM) can communicate successfully, have the client machine attempt to obtain a license from the license server. If this attempt is unsuccessful, review the LMGRD log to determine whether the license server received the request and, if the request was denied, identify the reason for the denial.

Attempt to License and Troubleshoot

Have the client machine request a license from the license server by launching the NI software that requires licensing:

1. For this test, it is recommended to rule out any locally activated licenses. To do this, move any license files from the <ProgramData>\National Instruments\License Manager\Licenses directory to a different location so that NI License Manager cannot detect them.
2. One way to accomplish this is to create a folder within the Licenses directory (for example, Hidden Local Licenses) and move all .lic files from the Licenses directory into this newly created folder.
3. After moving or editing any license files, be sure to click the Refresh button in NI License Manager. The moved license files should no longer appear under the Local Licenses tab.
4. Once all local licenses have been removed, attempt to request a license again by launching NI software on the client machine, such as LabVIEW, TestStand, DIAdem, etc.

If you are not prompted to activate or evaluate software, licensing has been successfully obtained. Open NI License Manager and navigate to the Network Licenses tab. Verify the license status, which is indicated by a green box or circle next to the license name.

If the software does not open as licensed, review the LMGRD log file located on the license server to help determine the source of the issue:

1. Open the LMGRD log found at <ProgramData>\National Instruments\License Manager\Data\lmgrd.log in a text editor.
2. Search for the client’s machine name or username in the log file. Specifically, look for lines that begin with one of the keywords listed below. Definitions for each keyword are provided for clarification:

• OUT: the listed license was successfully checked out by the client.
• IN: the listed license was checked back into the server by the client.
• DENIED: the listed license was requested by the client but denied by the server. The log should include the reason for the denial. Denial reasons may include, but are not limited to, the following:
  • The maximum number of license users has been reached.
  • All available licenses are reserved for other users.
  • The user or host is not included in the INCLUDE list for the requested feature.
• UNSUPPORTED: This message can occur for various reasons. It is typically harmless and does not affect the ability to check out licenses; however, in some cases, it may indicate communication issues, such as a compatibility mismatch between the server and the client.

The following is a sample of the lmgrd.log file:

Interpreting the Results

The Machine Name or Username Does Not Appear in the LMGRD Log

The licensing server is not receiving a request from the client. If the user/machine is getting denied a license, the log should provide reasoning as to why. 

The Reason for Denial Does Not Match the Volume License Manager Configuration

If the machine name or user name does not appear in the LMGRD log or the reason for denial does not match the Volume License Manager configuration, and if the other Troubleshooting Volume License Manager connectivity tutorials have been followed, it is recommended to contact NI support.