When trying to use Altair software with an on-premise license server, you may encounter the following error message:

(Err: 16) Rejected actively from license server

This error can occur when:

1. The license server is out of date.
2. You upgraded your license server but an older version is still running.
3. You are not authorized to access the license.
4. You are using a triad of server and not pointing to the main server.
5. Another service is running on port 6200.

To resolve this issue:

1. Check that your license server is updated to the latest version. Read this article for instructions on how to get and install the latest version.
2. Turn off and uninstall any older version of the license server.
3. Contact the person in charge of your license server to check whether group restrictions or group authorizations are preventing you from accessing licenses.
4. Make sure your ALTAIR_LICENSE_PATH variable points to all 3 servers in your triad, with the main server being listed first.
5. Configure your Altair license server to use a different port. You need to change the value of TCP_LISTEN_PORT in the altair-serv.cfg file, then restart your server. The ALTAIR_LICENSE_PATH variable needs to be modified accordingly.

If none of those suggestion helped you to solve your issue, please contact Altair support with the following information:

1. Exact version of your license server
2. altair-serv.cfg configuration file
3. server log file located in the logs sub-directory of the Altair license server installation
4. value of the ALTAIR_LICENSE_PATH variable on the client where the error is happening

Please note that items 1 through 3 are on the license server and you may need help from your IT to get them.