How to Upgrade from a Testing Build to Final RTM Version of Windows?

NOTE: This tutorial will help you in upgrading from Windows 7, Windows 8 and later operating system's testing version (such as Preview version, Beta version or RC version) to final RTM version which is not possible by default.

UPDATE 2: Tutorial updated for Windows 8.1 RTM version.

UPDATE 1: Tutorial updated for Windows 8 RTM version.

Consider the following scenario:

As soon as you run the setup installer, you get following error message:

Compatibility Report (saved to desktop)

You can't upgrade this prerelease version of Windows 7 / Windows 8 / Windows 8.1. Go online to see how to install Windows and keep your files and settings.


It happens because Microsoft doesn't allow you to upgrade from a testing build of Windows to final RTM version. Its always advisable to perform a clean installation of final version of Windows as the previously installed testing build might contain bugs and issues which may cause problems in future if you directly upgrade the testing build of Windows to RTM version. So you should always do a fresh installation of final version of a new Windows edition.

But sometimes you might need to upgrade the testing build of Windows to final RTM version. You can't afford a clean installation. In such case, this tutorial will help you.

Although Microsoft doesn't allow upgrading of a testing build of Windows to RTM version but its possible to upgrade by modifying a text file "cversion.ini" present in Windows setup directory.

If you also want to upgrade your already installed testing build of Windows 7, Windows 8 or Windows 8.1 to final RTM version, follow these simple steps:

1. First go to the folder containing the ISO file of RTM version of Windows 7, Windows 8 or Windows 8.1. Now extract the ISO file using 7-Zip.

2. Open the extracted setup folder and again open "Sources" folder inside it and look for "cversion.ini" file.

3. Open the INI file in Notepad and you'll see 3 lines similar to following:

4. This INI file contains MinClient and MinServer values which are used by Windows setup. MinClient value tells the setup what should be the minimum build number of existing Windows build to be able to upgrade it to RTM version of Windows.

As you can see in the above image, the MinClient value is set to 7233 in Windows 7 RTM setup file but the RC build number of Windows 7 was 7100. That means the MinClient number in Windows 7 RTM setup is greater than the build number of Windows 7 testing build, that's why you are unable to upgrade from previous testing build to Windows 7 RTM version.

To successfully upgrade your Windows, you just need to change the MinClient number in the INI file to exact or less than the build number of previous testing build which you have in your system.

  • For Windows 7 RTM upgrade, change MinClient value to 7000 in cversion.ini file
  • For Windows 8 RTM upgrade, change MinClient value to 7100 in cversion.ini file
  • For Windows 8.1 RTM upgrade, change MinClient value to 9431 in cversion.ini file

5. That's it. Save the file and run the setup.exe file again. Now it'll allow you to upgrade from testing builds of Windows 7, Windows 8 or Windows 8.1 to final RTM version.

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Posted in: Troubleshooting, Windows 7, Windows 8 / 8.1

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  • Thank you so much for the guide. It worked.

  • Worked like a charm for Windows 8. Thanks.

  • That was a lifesaver tip VG.

  • Which MinClient value I need to use to upgrade Windows 8.1 preview to RTM?

  • This guide works with Windows 8 (DreamSpark version) to Windows 8.1 RTM? Or it need to be available first on DreamSpark?

  • Wouldn't it be easier to just set them to a really low value (e.g. 1) for any version, or am I missing something?

  • VG

    ^^ It might work but I never tried it. There might be some check for minimum build number in each Windows setup which might cause problems if we set the MinClient value to 1 or similar numbers. Currently I dont have beta versions installed so cant check this.

    @Diogo Silva
    Windows ISO files are always same for all distribution channels such as MSDN, TechNet, Connect, etc.

    Tutorial has been updated. So please check it again.

  • Hey VG , a really frustrating error while installing Windows 8.1.....I downloaded the Windows 8.1 ISO , then I tried installing it as well . It asked me for entering my product key...But when I entered my windows 8 , it says me that the given key cannot be used to activate the current edition of Windows .

    I reinstalled Windows 8 on my PC and activated using the same key..It did activate . But I'm unable to install Windows 8.1 using he same key...

    It is an irony that Microsoft had said Windows 8 Keys Will Work With Windows 8.1 ... But the same isn't happening.....

  • VG

    ^^ The issue you mentioned is a known issue while installing leaked Windows 8.1 RTM. If you download Windows 8.1 RTM from MSDN or TechNet, you'll not face this issue.

    The workaround for the issue is first install Windows 8.1 RTM using a generic key available on Internet. Once it installs successfully, activate Windows using your genuine Windows 8 product key.

    The public Windows 8.1 RTM will install using Windows 8 product key.

  • Hey , its actually a setup file of my friend who downloaded it from , I think TechNet...

    So you mean to say if we enter this product key on October 18 , it will work , and not before that???

  • VG

    ^^ No. The public build which will be released on October 18, will be different and will support Windows 8 product key as far as I know. Its not an official statement from Microsoft.

    The builds downloaded from TechNet or MSDN will not allow you to use Windows 8 product key. But there is no need to worry as you already get free product keys as a part of your subscription.

  • The bad news VG , I tried to put the Generic Key but it still doesn't work....

  • VG

    ^^ Did you try Windows 8.1 generic key? I cant share the key but I looked on Google and found a working key which starts from 334NH.

  • Yes , I tried it , but still says the same error.....

  • K...thanks VG

  • The key that begins with 334NH says an error that "This Key Does Not Work With This Edition Of Windows . Try a different key."

  • VG

    ^^ There are different product keys available for Windows 8.1 RTM such as retail, pro, etc. Make sure you are using the correct product key. Cant help much.

  • I tried all the generic keys available (Core , Professional) but none worked

  • Actually we can upgrade to final version without any hacks. Tested fron upgrade windows 8.1 preview to windows 8.1 RTM. They show keep windows, program and user files

  • @leomate : That's not my problem . My problem is My Windows 8 key is not being accepted at Windows 8.1 Setup , but it is being accepted at Windows 8 Setup...

    I even tried all the generic keys available on the net , but none work on my setup

  • @Addy use advance token manager by josh cell software(search google) to backup ur windows 8 activation info,once u have the backup u get two files in the backup folder: tokens.dat and data.dat.
    Now after installing windows 8.1 u just need to put these files in c:\windows\system32\spp\store,when it ask to replace files click ok, also remember that file data.dat is hidden so enable show hidden files folder from folder options.Hope this helps,plz tell if it helped or not.

  • @Addy if u can't install create a modified iso with ei.cfg which would give u the option to install different versions, then use the keys u have to install. Basically u need to get the combination right for key and diff. versions,the starting letters of keys vary like:

    these r irrespective of whether u want to install 32 bit or 64 bit,so r u sure u have tried all the version or ask ur friend who downloaded it which version he downloaded.

  • Hey @rkkdjb ... Thanks , the version he downloaded was CoreSingleLanguage ... It worked as a charm.....

  • ^^happy to help you.

  • Hey VG , now I'm having a new problem , according to your post , if we enter 9431 in MinClient value in the cversion.ini file , we should be able to upgrade from Windows 8 to Windows 8.1 without losing any apps....But when I did this (even before doing this), I got an option to keep only my personal files .......

    I even tried values like 7000 , 7100 .... none worked....

  • is i download window 8 loader from this website to activate window 8 consumer preview

  • @Addy ok so I m assuming u r installing through a usb.So do this open notepad and type this:


    Just copy and paste this and save this as all type files and name it 'ei.cfg'(without quotes and save it as all files and not text).
    Now put this file into the sources folder present in ur win usb.Install as usual and then it should give u a option to custom install keeping ur apps,settings etc.Plz tell if this helps.

  • @aman deep
    That's pirating I can say.

  • Hey @rkkdjb , thanks for your concern , but I posted my problem after doing this ..... The problem still pertained since then....

  • Hey VG , I extracted my Windows 8.1 RTM Setup Files . In the cversion.ini file , the MinClient Value was 9458.0 . I changed it to 7600.0 . But When I launched the setup , it allows me to keep only my personal files.... Plz Help.....

  • Hey VG, any way to downgrade back from 8.1 RTM Pro to 8.1 Preview. I can't figure out how to activate 8.1 RTM and keep getting message to activate and I don't want to be bothered anymore. Thanks.

  • VG

    ^^ You can activate Windows 8.1 using your genuine Windows 8 product key. Did you try it?

  • I followed ur instructions but after installing it, i checked my pc info and its still showing windows 8.1 preview, why?

  • Hey VG, I followed ur instructions but after installing it, i checked my pc info and its still showing windows 8.1 preview, please why?

  • To upgrade from 8.1 preview, just run Windows store

  • just delete the "cversion.ini"..
    no need for editing..
    it works..

  • How to upgrade windows 7 to windows 8.1 free
    with all your personel file from windows 7

    Free Free dont want to buy from upgrade assiteten
    any tutorial guys

  • BUT after upgrading this way from a RC, and installing SP1, I cannot get windows updates to get a list of updates NOR start downloading them, it just cycles and NOTHING is done and I HAVE TRIED all THE wINDOWS updATEIN repairs methods all over the interenet including readiness..........waaaaaaaaaaaaaaaaaaaaaaaaahhhhh

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