After you install this update, Microsoft Skype for Business Server Unified Communications Web API (UCWA) will add the SameSite=None attribute to all cookies for supported browsers.
.NET does not support SameSite fully, so you need to append "SameSite=None" to cookie.Path to make this work.
Since “None” is a new value, old browsers will not recognize it and treat it as "SameSite=Strict". You need to make sure you do not set SameSite=None for browsers that don't support it. For more information, see SameSite=None: Known Incompatible Clients.
You can track updates to .NET for this issue, see Upcoming SameSite Cookie Changes in ASP.NET and ASP.NET Core.
How to get this update
To get this update, install one of the following updates: