Symptoms
In a Microsoft Skype for Business Server 2015 environment, users intermittently can't join a meeting through the meeting link. However, they can join the meeting by using the Microsoft Skype for Business client or Outlook. Additionally, users may receive the following error message:
Error: Invalid Conference organizer or Conference ID.
Resolution
To fix this issue, install the August 2021 cumulative update 6.0.9319.619 for for Skype for Business Server 2015 and Unified Communications Managed API 5.0 Runtime.
