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How to resolve the error 0x80073701(ERROR_SXS_ASSEMBLY_MISSING) when you are installing a service pack or update

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Symptom:

When you are installing a service pack or update for Windows 7 or 2008 R2, the update may fail to install with an error 0x80073701.

When you examine the CBS.log, you may find the followings were logged:

2011-03-01 10:31:14, Error CSI 00000010 (F) HRESULT_FROM_WIN32(ERROR_SXS_ASSEMBLY_MISSING) #396746# from Windows::ServicingAPI::CCSITransaction::ICSITransaction_PinDeployment(Flags = 0, a = 9e12b49121d141c9a55e48800acbaadd, Version = 8.0.7600.20820, pA = PROCESSOR_ARCHITECTURE_AMD64 (9), Culture neutral, VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral, cb = (null), s = (null), rid = [77]"Package_1_for_KB2447568~31bf3856ad364e35~amd64~~6.1.1.0.2447568-1_neutral_LDR", rah = [1]"3", manpath = (null), catpath = (null), ed = 0, disp = 0)[gle=0x80073701]
2011-03-01 10:31:14, Info CBS Failed to pin deployment while resolving Update: 2447568-1_neutral_LDR from file: (null) [HRESULT = 0x80073701 - ERROR_SXS_ASSEMBLY_MISSING]
2011-03-01 10:31:14, Info CBS Failed to resolve item[0] in Package: Package_1_for_KB2447568~31bf3856ad364e35~amd64~~6.1.1.0, Update: 2447568-1_neutral_LDR [HRESULT = 0x80073701 - ERROR_SXS_ASSEMBLY_MISSING]

Cause:

Error 0x80073701 is ERROR_SXS_ASSEMBLY_MISSING, it means there are some system files are missing, which caused the update installation failure.

Resolution:

To resolve the issue please try the following

1. Run the checksur.exe (System Update Readiness Tool) tool.
2. Run System File Checker. From the command line run the command sfc /scannow
3. Examine the language packs installed on the system. Uninstall the unnecessary language packs.
4. Review the cbs logs and uninstall the patches which were missing assemblies and reboot the server.
5. Reinstall Service Pack 1.

For advanced customer, you can manually examine which files are missing. For example, in the above CBS log, you can see the files for update KB2447568 are missing. To resolve this issue, you can either:

1. Copy the missing files from a good machine.

2. Download and install KB2447568 again.

Well, the repair install is the last choice but worth a try befor you give up. :-)

More information:

Description of the System Update Readiness Tool for Windows Vista, for Windows Server 2008, for Windows 7, and for Windows Server 2008 R2
https://support.microsoft.com/kb/947821

Comments

  • Anonymous
    January 01, 2003
    Mine turned out to be a permissions issue. Ran tweaking to reset permissions

  • Anonymous
    September 30, 2011
    The comment has been removed

  • Anonymous
    January 06, 2012
    The comment has been removed

  • Anonymous
    February 14, 2012
    Tried all of the above, without success. The only thing that worked was uninstall all Windows Updates (leaving framework and office updates), (in my case there were 132) only restart after uninstalling all. There were a couple which couldn't be uninstalled. After restarting try uninstall any remaining update and restart. After all that, SP1 standalone installation could finally be succesefully installed. Before doing anything change windowsupdates from automatic to manual download an install to avoid automatic reinstallation of everything.

  • Anonymous
    May 24, 2012
    Now that all the above has been done and the SP still does not install... what next?  Does anyone know where the missing assembly should be located (or where the installation routine is looking to find it) and if so has anyone attempted to copy it from a machine on which SP1 did successfully install and then put that copy on the troublesome machine? Did it resolve the problem?  

  • Anonymous
    May 12, 2013
    I have been researching this error for days and no one ESPECIALLY Microsoft will state what the heck it means or how to actually fix it, when anyone posts they got it fixed it is always after they have tried 40 or 50 things and none of them know what actually fixed it I think it is mostly luck. In the case I am working on today for a client, the readiness tool doesn't fail but SP1 does. Stand alone version or from windows update. Same error over and over and over and over and over and over and over and over....it's another case of a single error number being one possibility of 167 different things instead ....and since I have only tried 140 so far I sill have a bit of work ahead... Getting real fed up with the recommendation of re-installing windows...that is NOT an answer and that does not repair the ERROR they have in the sp. If a re-install works, then the sp install should also since its pretty doggone close to a reinstall of almost everything anyway....a sp should ALWAYS install and the engineers that think it doesn't have to should no longer work on service packs. Errors should give an indication of what really happened or it should be a different number. Microsoft if you keep telling customers to re-install, they just might re-install OSX, Linux, or any other OS that doesn't have your name on it....

  • Anonymous
    July 04, 2014
    For Free Window 7 Tech Support Contact Us: 1-800-935-0537
    http://computertechsupport.us/

  • Anonymous
    August 21, 2014
    I tried many suggestions that I found on the internet and none worked. I then interrogated my CBS.log file at great length and discovered several references to KB2883200.

    I removed it and now I am able to add roles again!

  • Anonymous
    July 03, 2015
    The comment has been removed

  • Anonymous
    July 08, 2015
    i solve this

    i download latest "Windows Update Agent" https://support.microsoft.com/en-us/kb/949104
    but there is same error - 0x80073701

    so i just extract(by winrar/7zip) files from WindowsUpdateAgent-7.6-x86.exe: WUA-Downlevel.exe and WUA-Win7SP1.exe

    and start first one WUA-Downlevel.exe
    after success install, i try to check windows updates - and magick! all work fine

  • Anonymous
    August 08, 2015
    Arthur: Dont work fo me

  • Anonymous
    August 25, 2015
    I have been grappling with this issue for quite a long while. Solutions 1 - 4 never had any influence on the 'sxs_assembly_missing" problem whatsoever. I tried other solutions that have been posted at one URL or another over the last few years, all to no useful effect. Finally, I happened to try an SP1 disk that I had created a couple of years ago with the SP1 executable and symbol files in msi format. That attempt completed normally, and after 144 'critical updates', and 48 'optional' updates, and something on the order of a dozen or more re-boots, I now have a fully updated version of Win7 Pro SP1 installed and working normally, on a GRUB-loader-based, dual-boot, Windows and Linux platform. I don't usually install MS symbol files, because I've never needed them until now. You'd think that MS could have taken 2 or 3 minutes to add a note to the download site with words to the effect, "...by the way, don't forget the symbol files."

  • Anonymous
    November 05, 2015
    Although correct system and fault codes given, the results are not given for the relevant categories and Microsoft support is not very good at all. Will probably revert to 8.1