Cannot install .NET Framework 1.0 service packs if .NET Framework 4 or 4.5 is installed

There are some known compatibility issues between .NET Framework 4 and 4.5 setup and .NET Framework 1.0 setup.  As a result, installing the .NET Framework 4 or 4.5 will set a registry key that prevents .NET Framework 1.0 setup from running afterwards.  That means that if you need to install both the .NET Framework 1.0 and 4 or 4.5 on the same computer, you need to install the .NET Framework 1.0 first, then install the .NET Framework 4 or 4.5.

I ran into a similar issue recently that I want to highlight as well because I didn’t find any official documentation about this behavior.  The registry key set by .NET Framework 4 and 4.5 setup will also prevent .NET Framework 1.0 service packs from running afterwards, even if you already have the .NET Framework 1.0 installed.  That means that if you need to install any .NET Framework 1.0 service packs and you have the .NET Framework 4 or 4.5 installed, you will need to do the following:

  1. Uninstall the .NET Framework 4 or 4.5
  2. Install the .NET Framework 1.0 service pack
  3. Re-install the .NET Framework 4 or 4.5

Behind the scenes, .NET Framework 1.0 setup includes a block that is implemented as a Type 19 custom action.  This custom action is sequenced so that it runs during initial install and repair.  Installing a service pack does the equivalent of a repair, which is why the block is triggered during service pack installation too.

Comments (8)
  1. Yuhong Bao says:

    So why did the standalone .NET 1.0 got only 7 years, not 10 years of support?

  2. Hi Yuhong Bao – The information in this blog post isn't related to the support window for the .NET Framework 1.0.  The underlying issue is that the team discovered some bugs in .NET Framework 1.0 setup after it shipped, and since the bugs were in the base setup package, it wasn't possible to fix them in a service pack because a service pack requires the base product to be installed first.  Instead, they decided to work around the bugs by enforcing a specific order of install (1.0 first, then 4 or 4.5) that is known to not trigger the bugs.

  3. John says:

    Would this also prevent .NET 1.1 from updating?  I have been having some issues with a server which will not allow me to install KB2742604 and the issue seems to be tied to v1.1 of .NET being corrupted in some way.  I have gone so far as to try the steps in your previous post:…/431385.aspx but receive an error from GACUtil.exe in the last step "The system cannot find the file specified" for every .dll in assemblylist.txt  

  4. Hi John – No, the issue in the post only affects the .NET Framework 1.0, not 1.1 or any other versions.

    Do you see the files from assemblylist.txt on your computer?  If they're missing, you might need to use the steps at…/how-to-repair-the-net-framework-2-0-and-3-0-on-windows-vista.aspx to run SFC to restore the files.  If that doesn't help, you might need to repair/reinstall Windows Server 2003 to fix this type of error.

  5. Michael says:

    This issue of not being able to install .NET 1.0 Framework after installation for .NET 4.0 is documented in the readme of .NET 4.0.   However it mentions nothing of Service Packs or Security Updates/Hotfix installation issues after .NET 4.0 is installed.  The .NET 4.5 Framework readme mentions nothing of .NET 1.0 in the release notes at all probably because it was out of support by the time .NET 4.5 was released.

    After uninstall of .NET 4.0/4.5, .NET 1.0 should be installed followed by .NET 1.0 SP3 and KB928367.   This should get you up-to-date as Windows Update would update you.   I don't know if you need any more Hotfixes after this install order, but do that before you install .NET 4.0/4.5

    From .NET 4.0 readme: The .NET Framework 1.0 cannot be installed after the .NET Framework 4 is installed

    The .NET Framework 1.0 cannot be installed after the .NET Framework 4 is installed. The .NET Framework 1.0 must be installed before the .NET Framework 4 is installed.

    To resolve this issue:

    1.Go to control panel and open programs and features.

    2.Uninstall the .NET Framework 4 Extended.

    3.Uninstall the .NET Framework 4 Client Profile.

    4.Install the .NET Framework 1.0.

    ***Modifying Readme File***

    5.Install the .NET Framework 1.0 Service Pack 3.

    6.Install the .Net Framework 1.0 Service Pack 3 Security Update (KB928367)

    ***End Modifying Readme File***

    5(or 7).Install the .NET Framework 4. 4.5

  6. Yuhong Bao says:

    @Michael: .NET Framework 1.0 actually ended support in July 2009.

  7. Naeem Ahmed Ch says:

    Very Helpful Colosseum  

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