Thank you for the post.
Since the operating system was upgraded, I would suggest uninstalling and reinstalling FileMaker Server 12.0v4 with the full installer found here:
Afterwards, update to FileMaker Server 12.0v5 found here:
The recommended version of Java for FileMaker Server 12 is Java 7 update 75.
At this time, our recommendation is to leave the Java security level at high, but add http://localhost:16000 in as an exception.
I solved the issue. It was Apple's default security settings for the new OS which had to be changed.