If you are using a FileMaker Pro database and want to continue doing so, don’t forget to check that your version of FileMaker Pro is compatible before you upgrade to OS X Yosemite or any other version of OS X above your current version. Here is the URL from filemaker.com.
As of 9:15 am, OS X Yosemite is not listed on FileMaker.com’s Compatibility web page. I hope to see Yosemite added to this list within 24 hours of the official Yosemite release — probably sooner. So check this page before upgrading.
If your current version of FileMaker Pro is not listed at all, you’ll want to wait longer and investigate filemaker forums and other means to determine the safety of using Yosemite.
Not the official word from FileMaker Inc. but MIT Information & Technology Knowledge base says the OSX Yosemite Gold Master 3 was OK for FileMaker Pro 13 but not for FileMaker Server 13 when I looked at it today.