Despite Microsoft not releasing Service Pack 3 for Windows Server 2008, the build number was raised to 6003. The full build tag of the new update is
6003.20489.vistasp2_ldr_escrow.190320-1700 and it was raised in KB4493471. Microsoft adressed this change in a KB article, but that post claims, that the build number was raised in
KB4489887, which is not true, KB4489887’s build tag is 6002.24566.x86fre.vistasp2_ldr_escrow.190311-1800, despite the blog post referring to build 6003.20491. According to WZor, 6003.20491 was compiled 8 days after the build that was officially released as part of the April Monthly Rollup.
Now, why is this important? In Windows Vista – Windows 10 v1507, the service pack number is derived from the last 4 bits of the build number. This means that build_number%16 should give you the service pack number. This decision was later lifted with Windows 10 v1511, but this is Windows Vista Server we’re talking about. Windows Server 2008 build 6003 is still Service Pack 2. Since the mainstream support of this operating system ended in 2015, it’s clear that we won’t be getting new service packs at all. This build number change may cause some apps to break though and detect this as Service Pack 3. If there is an app specifically hardcoded to work only on Server 2008 Service Pack 2, it may stop working, since it expects the build number to be 6002.
This is the first time in history that a minor Windows Update caused a full build number change. Nobody expected build 6003 to be ever compiled. For this reason alone, when first mentions of build 6003 were spotted on msbuilds, a lot of people were quick to call this fake.
Another thing I’d like to mention is that Windows Vista build 6003 will never officially exist because the client variant is not supported anymore, only the server variant is. You may be able to install this update manually though, since it’s essentially the same operating system.