Sentinel RMS Server License - I cannot launch Tekla Structural Designer - Error 3 or Error 5 is reported within the Status page of the License Manager. How can I resolve this?

Tekla Structural Designer
Tekla Tedds
Tekla Tedds for Word
Tekla Portal Frame Designer
Tekla Connection Designer
Not version-specific
Tekla Tedds Tekla Tedds for Word
Not version-specific
Tekla Structural Designer
Not version-specific
Tekla Portal Frame Designer
Not version-specific
Tekla Connection Designer
Error 3
Error 5
License Manager
Not environment-specific


I am using a Sentinel RMS Server License - Tekla Structural Designer appears to "hang" when attempting to launch.  After some delay the License Manager opens and and Error 3 or Error 5 is displayed within the Status page with the following text.  How can I resolve this?

  • Error [3]: Failed to resolve the server host

  • Error[5]: Cannot talk to the license server on host "HOSTNAME". Server not running??


These errors occur when using the Server (Sentinel RMS) license method and your computer (the 'client') cannot communicate with the License Server (which hosts the server license(s)).  There could be a number of reasons for this.  Go through and check the list of possible causes below in the order given.

  • Server Name Incorrect
  • IP Address Incorrect
  • Sentinel RMS License Manager not running
  • Check Network Communication is working
  • Anti-virus or Firewall blocking Communication
  • Connected over VPN

Server Name Incorrect

Check the server name is correct. 

  • Open the License Manager > System and User Settings by; pressing the Windows Key on your keyboard, or click the Windows button, and start typing System and User settings.
    System and user settings - run.png
  • Click on that option (App) when it appears on the Windows Start menu to open the Tekla Structural Licensing > System & User Settings
  • Select the "License Server" option in the tree menu on the left and check that the server name is correct. 
    check server name.png
  • The name must be the network name of the server computer.  You may need to check with your IT Administrator if you do not know what this is (we do not have this information as it is not stored by us)
  • More rarely, the Server name may not be being correctly resolved to the correct IP address of the license server.
    • This is usually related to internet router settings and may need to be investigated and addressed by an IT professional.  Please note that Tekla Support services cannot diagnose and fix fundamental network issues such as this.

IP Address Incorrect

If this is being used instead of the server name, check is is correct.

  • Using the server name is recommended, however the IP address of the server can be used instead.  If this is the case and the IP address of the server is wrong, or has changed, the client machine will not be able to communicate with the server.  The IP address of the license server must be static.  Check that the server IP address is correct.

The Sentinel RMS License Manager Service is not running  

This can only be checked on the licence server, so if you do not have access to it you will need to contact your IT Administrator.

Network Communication Working?

When all the above issues have been checked and resolved, try running a Ping test to check that network communication with the server is working.  

  • If you do not know what a ping test is, we recommend you seek the assistance your IT Admininstrator, or an IT professional if you do not have one.
  • Run a ping test of 8000 bytes from the client machine to the server to confirm that communication is possible - a ping test will not be blocked by the same hardware/software that may be blocking the License Service
  • If this test works OK move on to the sections below.  If it is not, then check with your IT Administrator/ IT professional that your network is operating correctly. 
    • Please note that Tekla Support services cannot diagnose and fix fundamental network issues such as this.

Anti-virus/ Firewall Blocking Communication

Communication may be being blocked by your Anti-virus (AV) / Firewall applications - these can prevent either the License Service or application from communicating with the license Server.  

  • The blocking may be occuring on the client, or the server, or both.  Hence you will need to check this on both clients and the server.
  • To quickly diagnose if this is the issue, you can temporarily disable the AV/ Firewall on the client and server.  To be clear this is not a proposed solution!  This is a quick and effective test to identify if this is the issue.
    • Hint - disable the AV/ Firewall successively on the client only, then the server only, to find if blocking of communication is occuring on only one of these.
  • When you have estabished where communication is being blocked - the client or the server or both - go to the problem computer(s) and set up the Exclusions as listed below.


To start with, create an exclusion on the server for the following file (the method of doing this will depend on theAV/ Firewall applications you are using):

  • C:\Program Files (x86)\Common Files\SafeNet Sentinel\Sentinel RMS License Manager\WinNT\lservnt.exe

If the issue persist, create exclusions for the following files on the client machine.

  • C:\Program Files (x86)\Common Files\Tekla\Structural\Licensing\LicenseManager.exe
  • C:\Program Files\Tekla\Structural\Structural Designer 2020\TSD.exe
    • (This is the location of the Structural Designer 2020 version application - if you are using version 2019i, then replace "2020" with "2019i" and so on)

If you wish to create specific port rules then please be aware that the client machine communicates with the server using UDP ANY PORT which is received by the server on UDP PORT 5093.

From the server, traffic is sent from UDP PORT 5093 which is received by the client on UDP ANY PORT.

Using Remote VPN Connection

If you are working remotely and connected to the license server using a VPN connection AV/ Firewall blocking issues can be more common.  For what to do in this case please refer to the following knowledge base article:

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