Application cannot connect to license server

What do you do when you get a message saying “application cannot connect to license server”?

Sometimes, after completing the installation of your new software, the application refuses to run, giving you a “Can’t connect to server” error.  When this happens,  the error message will look similar to the following:

Usually, this means one of the following has happened:

  • The license server is not running
  • The hostname or port # on the application’s computer doesn’t match where the license server is actually running
  • The license server (rlm) is running, but the ISV server for your application isn’t running for some reason
  • A firewall is blocking access to rlm or the ISV server
  • The license server machine is down

The first step in diagnosing this problem is to find out where the application thinks the license server should be running.  The most accurate way to do this is to use rlm diagnostics with the application.  Since RLM v8.0, every application which uses RLM has built-in diagnostics.  The procedure for running diagnostics is described in this article:

Once you know the hostname and port of the license server, you should log in to that host and verify if the license server is running.  You should see one process for the “rlm” generic server and a second one for your ISV server.  Depending on whether the ISV server is a binary or a settings file, the process listing will be a bit different.  On Unix systems, for an ISV server implemented as a settings file, the two process will look similar to the following (this is for the “reprise” ISV server):

For an ISV server binary, the output will look more like this:

In the windows task manager, you will see either 2 rlm processes or 1 named rlm and one with the name of your ISV server:

  • If you can find rlm running, but not your ISV server, you will need to look at the debug log from rlm to see why the ISV server isn’t running.   The simplest way to do this is to run rlm in a command window (on Windows) or from the shell on Unix.    Go to the directory where the license servers are installed, and run the command “rlm”.    If the problem is not apparent from the output of rlm, you should contatact the ISV who supplied your software – they should be able to help you get the servers running.
  • If both rlm and ISV servers are running on the server node, the problem could be that either you have a firewall installed on the server node which is not allowing your application to access either the rlm port, or the port of the ISV server.   If this is the case, configure your firewall to allow access to port “xxx”, and you can configure RLM to use a fixed port number for the ISV server by specifying the ISV server port, xxx,  on the ISV line as such:

ISV isvname port=xxx (if you have RLM v9.0 or later), or

ISV isvname isv-binary isv-options-file xxx (if you have pre-v9 RLM)

If  you see another cause of this problem, or have a different solution, please leave a comment.


  1. Mawary says:

    Hey, Matt

    Thanks for your great article but,

    I have some trouble with my application (CMG) as it can’t detect my license file on my campus server. RLM web interface show that ISV server is running however my CMG cannot detect the ISV server and refuse to run.

    Any idea what potentially cause of this? i have tried to unblock port with firewall and give no luck.


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