Fusion Registry Setting for FUSION_REFCOUNT_FILEPATH_GUID RRS feed

  • Question

  • I have a unique problem. I have to install some .Net 4.0 DLLs in a .Net 1.0 MSI.

    I've renamed the DLLs with a different extension so that the 1.0 MSI installs them as loose files.  I also have an executable being installed that will run and rename the DLLs and install them into the gac using

    Unfortunately, this method does not include an option to add a Fusion Reference and there is no Microsoft Supported API to add the Fusion Reference so in order to avoid them being accidentally uninstalled I have to add a Fusion Reference using
    In order to complete the registry setting I need to know what string value name to add to the following key:


    When I use GacUtil.exe with a FILEPATH argument of C:\test.txt when installing the same DLL one of my test systems creates a string value name of
    But, my other test system creates a string value name of
    Does anyone know what is being inserted by GacUtil?  What is f29ccddf and b208f3bf?  It's obvious that this is a double word i.e. 32 bits.  But, what does it represent?  How will I know what double word to add to my reference string name?

    Friday, October 16, 2015 3:27 PM


All replies

  • Hi Steven Wood,

    [this method does not include an option to add a Fusion Reference?]

    Do you want to add funsion reference(dll) to GAC or add dll to GAC using funsion api? Funsion API is unmanaged API, so we don't need to add them to GAC. If you want to add dll to GAC using funsion api, I found an article which contains detail steps. Link below is for your reference.

    Best Regards,
    Li Wang

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    Monday, October 19, 2015 1:39 AM
  • Hi Li,

    Yes, I found that before, but my personal efforts kept giving me exceptions.  As it turns out that page is just the help information to accompany the actual sample which is at:

    It's all good.

    Monday, October 19, 2015 4:09 PM