After installing or removing a patch or a feature windows often requires a reboot.
Is there a tool to see exactly why windows asks for this?

In w7 I found that HKLM\System\CurrentControlSet\Control\Session Manager\PendingFileRenameOperations often lists a bunch of actions which can just be ignored (like cleaning up some temp stuff) or can be solved without rebooting by just terminating  a process or a service which prevented the file rename operations in the current session.
I found lockhunter being a very helpful tool for this purpose.

My server 2012 says it requires a reboot but I don't see any pending file rename operations.
I cannot reboot the server right now so I am curious to know why exactly the server wants a reboot.
I want to judge myself about the criticality of the reason.
If windows says it needs a reboot, it well knows what the files are that need to be replaced so why can't it tell me?
As I said I often can resolve the PendingFileRenameOperations by hand.
If I then delete the PendingFileRenameOperations key windows does not request a reboot anymore.

On the server 2012 I don't see the PendingFileRenameOperations key and windows still says it wants a reboot.
So I want to know where else I need to look for the detailed reasons of the reboot windows pretends to require.

Hi,

Since this issue is related to Windows Server 2012, I recommend contact Windows Server 2012 Team so that you can get more professional suggestion about your question. For your reference:
https://social.technet.microsoft.com/Forums/windowsserver/en-US/home?forum=winserver8gen&filter=alltypes&sort=lastpostdesc

As far as I know, if you install security update and you may be prompted to restart your computer if one of the following conditions is true:
1. The security update updates a DLL that is loaded in one or more processes that are required by Windows.
2. The security update updates an .exe file that is currently running as a process that is required by Windows.
3. The security update updates a device driver that is currently being used and that is required by Windows.
4. The security update  makes changes to the registry.
5. The security update  makes changes to registry entries  that are read only when you start your computer.

For your question, I find an script to check if any Windows Server is pending for reboot: https://gallery.technet.microsoft.com/scriptcenter/How-to-check-if-any-4b1e53f2