How do I resolve the error "Communication failed" when running grbgetkey?

While running grbgetkey to retrieve a license file, you might receive the error:

Communication failed, check your network connection
or set variable HTTPS_PROXY if you need a proxy

If your computer is connected to the internet but requires a proxy, you can specify a username and password in the environment variables HTTPS_PROXY and HTTP_PROXY by setting them to http://username:password@proxy-server:port.

In addition, please verify with your IT team that portal.gurobi.com is whitelisted on your network firewall. Granting access to this address should resolve any restrictions imposed by the firewall.

Commercial license users

If your computer isn't connected to the Internet or if your network security system does not allow the command below to function, we also offer a manual license key process. See How do I generate a license file for a computer without internet access? for more information.

Named-User Academic license users

Please check the following conditions for the computer where you want to install the free academic license:

• The computer can communicate with the Gurobi User Portal.
• The computer is not using a proxy server.
• The grbgetkey program is not blocked by a personal firewall or an internet security program.

Further information

• How do I generate a license file for a computer without internet access?
• Where do I place the Gurobi license file (gurobi.lic)?
• What can I do to resolve an "ERROR 405" from grbgetkey?
• What can I do to resolve an "ERROR 303" from grbgetkey?