Weird issues when msxml3.dll fails

  • Symptoms
  • I’ve recently had the following symptoms on a computer:

    • Clicking on ‘properties’ after right click on ‘computer’ in the start menu doesn’t do anything


    • I cannot launch eventvwr.msc or eventvwr.exe without getting an error message although I can launch mmc.exe and load the snap-in successfully to read the eventlogs
    • Opening the Windows Update applet from the Control Panel doesn’t work
    • the AV UI fails
    • The volume shadow copy service complains all the time
      Volume Shadow Copy Service error: Unexpected error calling routine CoCreateInstance. hr = 0x80040154, Class not registered


    • The servicing stack is idle and running the System Update Readiness tool to fix Windows corruption errors fails with the following error message:
      Windows update could not be installed because of error 2147746132 “Class not registered”

      NB: I can still extract what’s in the Windows6.1-KB947821-v34-x64.msu file and run checksur.exe manually.

  • More clues
    • The WindowsUpdate.log file indicates:
    • The volume shadow copy service also reports
    • and clicking “manage” after right-clicking ‘computer in the start menu ends with the following error message:
      msxml3.dll is either not designed to run on Windows or it contains an error
  • What’s the problem
  • Everything says msxml3.dll has a problem. Right?

  • What’s the root cause
    • The msxml3.dll is actually empty:
    • and the CBS logs says, it started applying a package supposed to replace msxml3.dll
    • but 2 minutes later, it reported it cannot parse XML anymore
    • What happened during these 2 minutes….is actually a power loss 😦
  • My fix
  • # Gather all msxml3.dll files under %windir%
    $all = dir C:\Windows\* -inc msxml3.dll -rec -for -ea 0
    # restore the most recent version from the component store
    robocopy ($all | Where { $_.FullName -match "amd64" } | sort lastwritetime | Select -Last 1).Directory C:\Windows\system32  msxml3.dll /B
    # register the dll
    regsvr32 C:\Windows\system32\msxml3.dll
    # if that fails, try with the n-1 version
    robocopy ($all |
    Where { $_.FullName -match "amd64" } |
    sort lastwritetime |
    Select -last 2)[0].Directory C:\Windows\system32  msxml3.dll /B
    regsvr32 C:\Windows\system32\msxml3.dll
  • Steps to reproduce the problem
  • # unregister the dll
    regsvr32 /u C:\Windows\system32\msxml3.dll
    # create an empty file
    New-Item C:\Windows\temp -Name msxml3.dll -ItemType File
    # stop services that lock msxml3.dll
    Stop-Service -Name WSearch,WinRM -Verbose
    # kill processes that lock msxml3.dll
    taskkill /im explorer* /f
    # restore the file (ab)using the backup privilege
    robocopy C:\Windows\temp c:\windows\system32 msxml3.dll /r:0 /B

    Trigger ConfigMgr client actions

    A few weeks ago, I came across the following article on refreshing the System Center Configuration Management client

    Whenever I see a script, I always wonder, could it be done with a oneliner ?

    As long as the script doesn’t care about the order of the ConfigMgr actions to be performed, yes, it’s achievable this way:

    (New-Object -COM 'CPApplet.CPAppletMgr').GetClientActions() | 
    Where { 
        $_.Name -match "(\sPolicy$)|(Collection\sCycle$)|(Updates)"
    } | ForEach-Object {
        try {
            Write-Verbose -Message "Successfully executed $($_.Name)" -Verbose
        } catch {
            Write-Warning -Message "Failed to execute $($_.Name)"

    I’ve even added some filtering on action names and error handling.

    There’s always more than one way to skin a cat with PowerShell 😉

    How to use WDS to PXE Boot a Nano Server VHD with PowerShell

    Last week I was renewed as a Windows PowerShell MVP MVP-2015-award, my article about how to use WDS to PXE Boot a Nano Server VHD with PowerShell was published on PowerShell Magazine and even mentioned on the Nano Server blog. Awesome, isn’t it 😀
    I’d like to thank everyone who enjoys my work, reads my blog, supported me and helped me along the way. I wouldn’t have been awarded without you. Again, a big thank you! I’m very pleased and honoured to receive this award and be part of this amazing PowerShell community 🙂

    PowerShell oneliner contest

    The pipeline in PowerShell offers an avenue to solve many issues with oneliners.
    My fellow Windows PowerShell MVP Carlo Mancini proposed a very interesting and high quality oneliner contest. Perfect, challenge accepted 😀
    After reading the rules twice, I jumped into trying to figure out what’s the best approach to get the shortest solution for each puzzle. I usually focus on the approach before trying to shorten my solution because when you started digging in a hole, it’s hard to get out of it and come with a brand new approach to solve the puzzle.

    • Task 1: get the absolute value of the highest double floating point in an array

    I noticed that the match operator with a regular expression allowed to filter out only double.

    $n = -1,-2,-5,-8.9,'b',-9.11,-6,-3,-2,-9.1,-1,-1.4,'a'
    # match with regular expression
    $n -match '\d\.'
    # vs. a more classic approach
    $n | ? { $_ -is [double] }

    There were only negative double numbers in the array. To get the shortest absolute value, I just multiplied by -1 instead of using the abs method of the [math] .Net class.

    # .Net abs approach
    # vs. me cheating 😉

    After bringing all the pieces together, my shortest solution for task 1 is:

    # task 1


    • Task 2: display 12345 as a int32 without using digits

    To solve this task, my idea/approach was to use hexadecimal and do some substractions

    0xb-0xa -eq 1
    0xc-0xa -eq 2
    0xd-0xa -eq 3
    0xe-0xa -eq 4
    0xf-0xa -eq 5

    …except that I can’t use the leading 0.
    So, I wondered how do I get a hexadecimal without using the 0x notation.
    Well the answer is:

    # you can actually do 
    [char]'f' - [char]'a'

    My shortest solution for task 2 is:

    # task 2


    • Task 3: Display PowerShell from ‘X ‘

    When I saw this puzzle, I immediately thought, use only 1 occurrence of ‘X ‘, get rid of the whitespace behind X and use the ascii table to get P from X, o from X, w from X,…

    My shortest solution was:

    #task 3 split for readability
    [char]($_+[int][char]('X '-replace' ',''))


    PowerShell rocks 😎 and Bravo Carlo, I enjoyed this very nice contest 🙂

    Bonus: my favourite PS golfer Bartek also proposed his solutions: