Windows system administrators have grown to expect patches from Microsoft on the second Tuesday of each month. The software giant formalized the practice of releasing security patches at the same time each month all the way back in 2003. Microsoft Patch Tuesday was supposed to take place on Valentine's Day this month, and it was expected to contain a fix for a zero-day bug in the SMB file-sharing protocol. It looks like something broke down, though, since the February patch has been scrapped and delayed until next month, meaning the SMB bug will remain unpatched until then.
In addition to the anticipated SMB bug fix, this month's patch would also mark a step towards changing the way updates are delivered to Windows 7, 8.1, Server 2008 R2, Server 2012, and Server 2012 R2. Microsoft has been moving its older operating systems towards a cumulative update model similar to the one it uses for Windows 10.
Microsoft didn't release any information about the reason for the delay, but ZDNet reports that a a snafu in Microsoft's build system is responsible for the postponed update. Whatever the reason, if testing indicated that there was a problem with the patch, the decision to delay was probably the right one.