This message can occur when you are trying to activate/reactivate/revoke an Individual license of ExtendSim.
It indicates that there is a basic issue (network initialization failure, unable to read or write, etc.) that is preventing the automatic process. In this case, a manual process is required and you should get a second error message that allows you to generate a text file to send to .
If you don't get that second error message, temporarily disconnect from the network, launch ExtendSim, and try again. That will force ExtendSim to present a dialog for generating a text file for a manual process. After the text file is generated (by default it will be placed at the top of your Documents folder), reconnect to the internet and email the text file to .