Read this before you install Java update - 8.151
Yesterday we installed the new Java Update 8.151 on a FMS15 / FMPA 14 on Windows 2012 server configuration.
Webdirect stopped working correctly immediately: blank screen, no databases to open!
After lots of research we decided to restore a VMware server snapshot: don't do that.
It resulted in a conflict of standard Filemaker certificate and our domain certificate.
The solution we had to apply was: go back to Java 8.141 and renew the certificate installations in IIS and FMS.
We don't know for sure but maybe just the re-installation of Java 8.141 could have solved the problem as well.