The WordPress core project has a strong commitment to backwards compatibility. This commitment means that themes, plugins, and custom code continues to function when WordPress core is updated. At The Theme Foundry, we adhere to WordPress’ best practices when developing our themes to make sure that WordPress core upgrades go as smoothly as possible.
Fortunately, we have ironed out all of these issues and updated all of our themes to be fully compatible with WordPress 3.9. If you are a current customer, we recommend updating your theme when you update to WordPress 3.9 in order for everything to function smoothly. WordPress 3.9 is a great update and we are excited that you can enjoy it knowing that your theme is ready for it.