How-To Geek

Why Do Application Installs Make You Reboot and Close Other Apps?


It’s happened to everybody at some point—you go to install a new application, and Windows tells you to reboot first. Or reboot after. Or it asks you to close out of every other application first. Why does it do that?

In today’s geek lesson we’ll explain exactly why Windows can be so irritating with all this rebooting, and hopefully give you a better perspective into why things work this way.

So Why Are Installers Annoying?

The short answer is that most installers are annoying because they either aren’t written very well, or they integrate too deep into Windows to be able to copy system files and start everything necessary without a reboot.

The problem is compounded because Windows applications often use DLL (dynamic link library) files that are shared between more than one application. It’s a nice idea, but when it comes to installing and uninstalling applications it can be irritating to need to reboot. The really sad thing is that many applications these days are completely self-contained and aren’t replacing built-in Windows DLLs, but their installers still make you reboot.

Here’s a couple of instances where installers might be annoying:

  • If the application you’re installing needs to copy new versions of files that are currently in use by another application, it will either prompt you to close all other applications, or it will make you reboot.
  • If there’s a previous installation or Windows Update that has pending changes requiring a reboot, some installations will fail and ask you to reboot first.
  • If the application you are installing has a plugin for another application, like an Explorer context menu addition, or a browser plugin, it will prompt you to reboot or close the other applications.
  • Sometimes badly written installers will ask you to reboot because they don’t start up the required services on their own.

Let’s take a closer look at some of these instances, so you can fully understand what’s going on.

In-Use Files Need to be Copied on Reboot

If the application installer needs to copy some files but they are currently being used, or are system files in the case of Windows Update, it will utilize a Pending feature in Windows that allows an installer to specify that a file operation happens after a reboot, and before everything in Windows has started up.

The installer will write a key to the following location in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager

If you’ve received an error saying that you need to reboot first, you can open up this key and you’ll see all of the files that need to be replaced on the next reboot.


You probably do not want to mess with the contents of this key, or else things will quickly start to become weird. There are some very rare instances where this key doesn’t get emptied even after multiple reboots, and you might have to wipe the contents of the key—but you should probably avoid doing that unless you are very certain.

Installation Already In Progress

Some installers won’t start up if there’s a current installation in progress, so they will check the following key to see if there’s an installation already happening:


I don’t have a screenshot for this one, but you can get the idea from the name of the key.

Windows Update Makes You Reboot

If you’re getting a message saying that you can’t install an application until you restart your computer, it’s because of Windows Update requiring a forced reboot. So, for example, if you’re getting this error message:


It’s because you probably clicked Postpone when you saw this dialog pop up:


If you head into the registry, you’ll see that there’s a RebootRequired key at this location in the registry:

CurrentVersion\WindowsUpdate\Auto Update

There’s a whole bunch of GUID values over on the right-hand side, and while they don’t pertain to anything in the registry, the fact that they are there is what is triggering that message.


Technically you could probably export the contents of the key, install the application, and then put them back—but it could break something, and rebooting isn’t that painful is it?

So now you’ve learned a little more about why application installers work the way they do. Is there anything else you’d like to know? Explain your frustrations in the comments, and we’ll see if we can’t shed some light on them.

Lowell Heddings, better known online as the How-To Geek, spends all his free time bringing you fresh geekery on a daily basis. You can follow him on if you'd like.

  • Published 10/6/10

Comments (26)

  1. JasonCook599

    This is one of the MANY reason Linux is better than Windows. A reboot is only required for a Kernel upgrade. You are not required to restart after installing an application.

  2. Anna

    Thanks for the article. Now I have to send it to my parents so they can understand.

  3. Dave

    Rebooting takes 30 seconds. It’s not like you need to do this several times a day or anything…

  4. Mudslinger

    I agree with JasonCook599 – Linux design is so much better and stable – that if things were written properly then the computer would barely need to reboot! – This has been a requirement of server based systems (where linux has come from) – why can’t it also be part of normal end-user experience?

  5. Lisa

    Agreed with Jason and Mudslinger…Linux handles updates so much better than Windows. Everything gets updated all at once, without a flurry of beeps, flashing windows, and the inevitable reboot.

    Now, if I didn’t have to restart Firefox when I updated my extensions…


  6. Barry Weiss

    Thanks for the article! It’s great to get a better understanding of the inner-workings of Windows. I am so glad I’ve discovered this site. So full of useful stuff!

  7. digitalrefuse

    I really appreciate this article… as a Support Engineer, I have to explain this kind of stuff on a very, very regular basis and you’ve captured it quite nicely. The only thing I would add is information about applications that install kernel level drivers.

    Microsoft does not provide the ability to replace most kernel level drivers (filter drivers, graphics drivers etc) without a reboot. Because of this, a lot of applications that require kernel driver updates will not function completely until you reboot – this is more likely to be seen on upgrades than initial installs.

    As far as Windows being inferior to GNU/Linux because of this, I’d have to argue that there are pros and cons of both methods… But it’s mostly because Windows allows/requires so many drivers to run in kernel space whereas nearly everything on GUI/Linux is running in user space… Also, I may be wrong, but if you’re loading a new kernel object, I’m about 99% sure you have to reboot before it’ll actually load.

  8. Kevin

    I agree with Dave. You don’t install updates and apps everyday and a reboot doesn’t take an hour.

  9. The Geek


    That’s a very good point about the kernel level drivers.

    Also, to all the Linux fanboys – the point I was trying to make is that the problem is because of Applications, and not necessarily because of Windows.

    Kernel updates and core library updates (like glibc) require rebooting your Linux box, just like kernel-level and very low-level stuff on Windows does.

  10. Jamshed

    very informative

  11. KayDat

    For those who are afraid (or too lazy) to go registry diving, a tool called WhyReboot ( takes a text dump of the registry string for easy viewing. You might need to run as admin for it to work though.

  12. The Geek


    Thanks for the link – I think there’s a couple of apps that show you the same thing, but that’s a pretty simple one.

  13. Hassan

    Very nice info.

  14. Col

    Having just rebooted a laptop at least 12 times to get Vista up to date after a factory restore image had to be used and put it to pre SP1 condition I felt drained. Never mind the repetitive deselction, hide update
    for the bloat that Microsoft wanted to shove on to it. A typical check for updates, selection of updates, hide updates, downloading updates, installing updates and reboot of windows took 30 minutes per go.

  15. John Fowles

    Whilst this is no doubt a most interesting and detailed disertation I am not convinced that I need to know or even understand it all.My personal problem with rebooting as required with some programs is not the length of time such a reboot will take but that before I begin the installation I might well have important unfinished with windows open such as unsaved text files, uncompleted downloads or websites I had struggled to find open but as far as I can see none of these affected installation programs provide absolutely no warning that a reboot will be necessary so that you can take appropriate saving etc action before commencing the installation neither do they spell out why a reboot is necessary or what problems if any would arise if one is so bold as to ignore the instruction and carry on regardless to open the program as is (I generally find that it does open wih no obvious lack of features thus confirming in my mind that the reboot was by no means essential in almost all cases).
    So yes it behooves the software’s compilers to think more carefully why they have added this often superfluous and irritating requirement

  16. nobbywebfoot

    I am now happily retired but if I had to go to sea in a ship that was built, equipped and manned like very many pieces of computer software are today it is unlikely I would be here now to wonder.
    But this is the way things are now. I feel that this atitude is an unconscious effort to compensate and add some uncertainty and fear induced adrenaline to the extremely dull lives we lead now.
    This does however have at least one drawback the constant irritation leads to a surfeit of the jitter juice in our systems which we try and burn up with constant complaint.
    If you are young it is far better to go out and kick a ball around or in my elderly case kick next door’s cat for shitting in my garden!
    Better still make the world a better place by shooting a politician or a banker this will earn you a certain bonus of a holiday gauranteed to have many moments of utter peace made all the more piquant by many moments of utter terror.

  17. Roi


  18. Darryl C Gardner

    Try this. Install only Windows and get its updates.

    Even though no kernel changes are made, good ol’ MS forces you to reboot.

    So don’t accuse non-MS applications of being the sole cause.

    Too bad MS chooses to aggravate their customers with this kind of BS, but that’s the way it is.

    By comparison, I have yet to see any Linux distro reboot when no kernel changes are involved.

    Maybe MS is so intent on destroying Linux because Linux does things right. (Hints: stability, security, price, bug fixes done in a timely manner rather than a second Tuesday sometime in the future, high degree of customization builtin.)

  19. loulou

    i have forgot the password on my laptop what can i do

  20. Ekstor

    To all Linux fans, Linux is a wonderful option, but please understand that IT IS NOT A VIABLE FOR EVERYONE!! Thank you. Let’s move on.

  21. T800

    Linux can not be compared to Windows as the kernel architectures are completely different.

    Immediate rebooting can be avoided using hot-patching where possible, but few applications do it.

  22. Al S

    I’m suprised that there are not a bunch of Apple OSx Fans chirping in about how superior they are by spending theice the amount of $$$$$$$ for an MAC.

  23. rocketmouse

    @Al S
    I’m sorry you missed me. Although, I’m not chirping, just very happy I only restart my MacBook ~once/week. Sometimes more often, but rarely. I haven’t actually felt the need to time how long it takes to restart it but it sure feels a lot faster than the ~2-5 minutes my own Windows installation used to take.
    I used to work as a computer systems engineer – a fancy way of saying I was the go-to guy when something went wrong in Windows.
    Do you need another explanation of why I switched?
    Oh, and as far as $$$$$$$ go, my computer is now six years old and still going strong under heavy usage. Yes, I bought it while I was still working, with the $$$$$$$ I made off of supporting Windows…

  24. Cody k

    I would suggest to the person who asked the initial question that they investigate WHY their computer takes so long to reboot. There are a number of ways to speed up the process, via the BIOS or msconfig. If they’re using XP, they should also check their startup folder in the start menu. A lot of programs (Windows and Yahoo Messengers, for example) that will default to starting themselves when Windows boots. I also recommend doing a fresh install of Windows periodically just to keep things running smoothly. If you are backing up your essential files regularly like a good computer user, this is not a terribly onerous task, and always keeps your computer running in optimal condition.

  25. Norbert Rehaut

    A lesson in what to leave or take out of the Win XP Start Up File and why, could save users a lot of time to start up there system! I have seen computers with upwards of 100 programs start up at start up!

    My XP system takes 1 Minute and 3 seconds to stare and that is a long time! I keep my systems start up programs to a minimum. Programs that are in the start up file that I don’t use to often I take out of this file. So what if it takes an extra few seconds to start the first time I load them. I have deleted the entire Start Up file and let windows put in only what it wants at start up,

  26. Nissim Hadar

    Cody k – do you work for Microsoft?

    Why should the average user know what a BIOS is or that msconfig exists?

    Reinstall Windows? Is Windows really that bad? If I was a good computer user I would surely use a good operating system…..

    No – what you are saying is totally unacceptable. Not by me, a professional programmer, nor by my mother, who knows nada.

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