Who is this article for?
CrashPlan for Small Business, no.
Code42 for Enterprise, yes.
Link: Product plans and features.
This article applies to version 4.
The enterprise server software is fully compatible with Apple's OS X Mavericks version 10.9. However, you may need to install or reinstall Java after upgrading your host server operating system to OS X Mavericks because Apple no longer bundles Java with the operating system.
OS X servers upgraded to OS X Mavericks (OS X v10.9) running enterprise server version 3.8.2010 and later
To resolve the issue, download and install the Oracle Java Development Kit (JDK) on your host server.