This error message usually indicates that there is a problem resolving the hostname of the license manager machine. The license server's hostname must be resolvable for MATLAB to connect to it. To test this, we need to use the ping application, which is a command line utility:
- On Windows 8, 8.1, or 10, press the Windows key to invoke a global search, and then enter the command "cmd".
- On Windows Vista or 7, enter the command "cmd" into the "Search programs and files" prompt located at the bottom of the Start menu.
- On Windows XP, enter the command "cmd" into a Run prompt, which is accessed from the Start menu.
- On Mac OS X, launch the application "Terminal.app," located in the /Applications/Utilities folder.
After launching the command line interface, enter this command:
where <hostname> is the hostname of the license server as it appears on the SERVER line of your license file.
For version R2008a or later, the license file is named network.lic and is found under $MATLAB/licenses.
where $MATLAB is your root MATLAB installation directory.
If the output of the above command comes back as 'unreachable' or 'unresolvable', then contact your System Administrator and have them address this issue. Alternatively, if you are unable to resolve the hostname of the license server, but can ping the IP Address of the license server, you can replace hostname in the SERVER line of your local license with the IP Address of the license server. To do so:
1. Navigate to $MATLAB/licenses on your machine.
2. Open network.lic with WordPad (Windows) or TextEdit (Mac). Do not open the file with Notepad.
3. In the SERVER line, the second item is the hostname. Replace this with the IP address.
4. Save the file and launch MATLAB to test if MATLAB was able to connect to the license server.
NOTE: If your license server does not have a static IP, then this workaround will stop working when the DHCP lease is updated. You should contact your license administrator to try and resolve the issue with hostname resolution if your license server does not have a static IP.
If MATLAB is still unable to connect to the license server even though you can ping it successfully, there may be one or more firewalls blocking the connection between the MATLAB client and the MATLAB license server. The license manager communicates on two ports that must be opened through the firewall(s). If there is a firewall running, contact your System Administrator to open the necessary ports in the firewall.
For more information about the port the license manager uses, see the following Article:
What ports does the MATLAB license manager use, and how can I set those ports?
For more information about checking your ports, see the Article:
How can I check if the ports between license manager and client are blocked?