When you use a valid name to create a persistent chat room in Italian version of Microsoft Skype for Business Server 2015, you receive the following message:
Il nome non è valido.
This message is displayed in green and indicates that the name is not valid.
Instead, you expect to receive the following message that indicates that the name is valid:
Il nome è valido.
To fix this issue, install the August 2021 cumulative update 6.0.9319.619 for Skype for Business Server 2015, Web Components Server.