Apple recently introduced new MacOS 10.13 High Sierra. Short version: If you use Pro Tools, don’t upgrade.
Main point why we don’t recommend upgrading for some time is that High Sierra introduces a completely new file system called APFS and new file systems historically tend to introduce unforeseen deep level issues. APFS is a very modern file system and has some very cool features so at some point in the future, it will probably speed up your workflow with better space management, speed and data security. But for now, we seriously recommend not to upgrade to High Sierra. Don’t hesitate to contact us if you have more or geekier questions.