Software that ran successfully in previous versions of an operating system will not necessarily work with the current version of Windows 10. Possible reasons for this may include new security features or operating system properties, as well as the discontinuation of functions or services. As a result, the use of certain software may be limited or impossible. Examples of enabled security features that may be the cause of compatibility problems with new versions of Windows include User Account Control (UAC) or, with 64-bit versions of the operating system, Kernel Patch Guard. In addition, signed drivers could be necessary, but unavailable for older devices.