SQL Server 2008 setup Error – Microsoft .NET Framework 3.5 installation has failed. I know i have it installed already!

I recently worked with a customer who ran into an interesting situation. The issue deals with SQL Server 2008 RTM setup.

He is trying to install SQL Server 2008 Enterprise on a Windows 2008 x64 box. As soon as we click ‘setup.exe’, we get below pop-up.


When we check from Control Panel –> Add/Remove Programs, I can clearly see Microsoft .NET Framework 3.5 SP1 installed.

Then why this error?

Started with the few basic check of looking into Setup Bootstrap logs, but there were none!!! means setup error has not even logged.

The came an interesting revelation: Customer informed that he was able to successfully install SQL Server 2008 32 bit, on different box, using same installer.

This gave me a clue to take a closer look at the SQL Installer. I started looking into x64 folder, comparing them to our own SQL installer library. And, my suspicions were validated as I could find several file/folders missing within x64 folder.

Very next thing I did was to list the missing folders, rename then at my end and then try simulating the error (In Microsoft Support, we love to re-produce the issue and find a solution for it) and I could get the same error, whoa! So this is a case of SQL media corruption.

Resolution then become simple as we just replaced the corrupt media with fresh one and then customer was able to install SQL Server 2008 successfully.

Thanks for reading!

Disclaimer: I work at Microsoft. Everything here, though, is my personal opinion and is not read or approved by Microsoft before it is posted. No warranties or other guarantees will be offered as to the quality of the opinions or anything else offered here.

Comments (4)

  1. acassanova says:

    I had the very same problem with SQL Server 2008 developer edition. I copied the media content to my hard drive and replace the "redist" folder. The "redist" folder was corrupted on the DVD, thus I was unable to get pass the .net 3.5 error. Once I replaced the folder with a working copy it installed without any other issues.

  2. varund says:

    Thanks acassanova for shring this.

    As an alternate, if you find that DvD/Media is corrupt, you can always consider downloading the SQL Installer from MSDN (using login credentials).


  3. divesh says:

    i am also facing the same problem please let me how to over come the error i did not understood what is x64 folder pls help me out

  4. Varun_SQL says:

    Hi Divesh,

    Please be aware, SQL Server Setup requires and installs the below .Net components required by the product:

    • .NET Framework 3.5 SP1

    Now, if you are getting error I have discussed above, i.e. as you click ‘setup.exe’, then I could be a corruption

    with SQL Server Media. In my case, there were few files missing in below folder:


    Here's a quick steps to confirm media corruption:

    1. If you are trying to install x64 SQL version then try running setup on x86 (32 bit server)

    2. See if the installer runs fine

    3. If it does, then some files might be missing in x64 folder


    – Download the SQL Server Setup files again from MSDN or Get a clean install DVD

    Hope this helps

    Varun Dhawan

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