Skype for Business Meeting Failed: Content was blocked because it was not signed by a valid security certificate
This issue also pop's up with Lync Meeting, not only with Skype for Business Meetings.
Content was blocked because it was not signed by a valid security certificate
After investigation, I saw this was most likely related to changes in Skype for Business Client Update from Januar 2016: https://support.microsoft.com/en-us/kb/3114502
It implements a new and proper described certificate validation procedure for all SIMPLE URL's. (Note:This issue can't be replicated each time, therefore you have to consider this as "possible issue")
As I described earlier in my blog: http://lyncuc.blogspot.de/2015/10/wildcard-certificate-support-in-skype.html
It is absolute curial following the infrastructure recommendations from Microsoft, regardless if it might work or not. Once there will be an update …