It means there was an issue on the EU D3 Region servers impacting game creation. In this case, the impacted players are not Silenced. It is another issue causing the error message. Blizz is aware of it.
1 post
Blizzard
Hello everybody,
First of all, I apologize for the recurring problem with the “group leader” error message. This problem has occurred in the past and has been resolved. But now it seems to be back again.
We have forwarded your reports to our quality assurance department and the developers, who are already intensively investigating the problem and will fix it as soon as possible.
In the meantime, we can only ask for your patience and hope for your understanding. Please rest assured that we are listening to you and are already working on fixing the problem.
Thank you very much for your understanding so far!