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

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

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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~~", 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~~, Update: 2447568-1_neutral_LDR [HRESULT = 0x80073701 - ERROR_SXS_ASSEMBLY_MISSING]


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


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

  • Ik vind het beneden alle peil dat er blijkbaar een fout in Windows 7 zit (er ontbreekt een sxs assembly, wat dat ook mag zijn) en dat je gewoon aan je lot over gelaten wordt.

    Het zou fair zijn als je gewoon deze ontbrekende delen in een bestand kreeg aangeboden!!!!. Je hebt toch voor je LEGITIEME Windows 7 betaald????'

    Sorry hoor, ik voel me zwaar genaaid!

  • There is a lot there is written out there about this error, which not only blocks SP1 update, but also IE 9 upgrade and changing of windows components (e.g. trying to add telnet client).  A lot of people, like myself, find that microsoft fixit, system update readiness tool, sfc /scannow to be useless.  

    What DOES work is step #3 and #4, as outlined above.  Another link that explains this is here:

    For myself, I had to install French language on an Asus UL30 notebook bought from Amazon (don't ask me why french) and uninstall one of the updates which was logged in CBS.log.  You don't need to uninstall all the updates like some blogs suggest.  Just find the ones that are having this  ERROR_SXS_ASSEMBLY_MISSING error.

    There are also recommendations out there about doing an inplace upgrade.  For those of you without an original CD because your system came installed, like mine, this is probably the only way, other than restoring your system and reinstalling all your software.  Even then, it appears from the blogs that SP1 might still not install with a fresh system.

    Good luck!

  • 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.

  • 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?  

  • 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'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....

  • Mine turned out to be a permissions issue. Ran tweaking to reset permissions

  • For Free Window 7 Tech Support Contact Us: 1-800-935-0537

  • 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!

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