When you configure multiple Microsoft Skype For Business Front-End pools on computers that are running Windows Server 2016, the Skype For Business Server Front-End service (RTCSrv.exe process) may be unable to start and crash in crypt32.dll.

This issue occurs because the certificate chain of a certificate that's used by a Front-End server in a different pool cannot be validated.

To fix this issue, install the following updates:

•  May 2017 cumulative update 6.0.9319.281 for Skype for Business Server 2015, core components
• May 2017 cumulative update 6.0.9319.281 for Skype for Business Server 2015, Front End server and Edge server
• May 2017 cumulative update 6.0.9319.281 for Skype for Business Server 2015, Unified Communications Managed API 5.0 Runtime