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I use Visual Studio 2012 for a WPF project needing (at least) .NET Framework 4.0. I have 4.5 already installed, but people with Windows XP cannot install the application (because 4.5 does not run on Windows XP). I use ClickOnce as the deployment application.

When I try to intall version 4.0, I get the error (translated from Dutch so the English version might be a bit different):

The same or a higher version of .NET Framework 4 is already installed on this computer

How can I fix this?

Peter Mortensen
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Michel Keijzers
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3 Answers3

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.NET 4.5 is an add-on to .NET 4.0 in terms of the CLR, and as such, when you install .NET 4.5, it includes 4.0. There is a known issue with ClickOnce when it is generated on a machine that has .NET 4.5 installed.

Visual Studio 2012 Update 1 is supposed to fix this issue.

You can set the .NET framework version for your .NET applications inside Visual Studio. When you want to publish a Windows XP compatible version, you should always select .NET 4 or lower as the target framework.

The .NET 4.0 Framework should be listed side by side with 4.5.

Enter image description here

This is on a normally installed Windows 8 machine, Visual Studio 2012 Ultimate, without having to install any other framework or SDK.

Peter Mortensen
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jessehouwing
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  • However, I cannot select 2.0, 3.0, 3.5 and 4.5. Version 4.0 is not in the list and when I try Install Other Frameworks and select anythink like 4.0 the installer displays I cannot install it becaue the version I have (4.5) is higher. – Michel Keijzers Jan 28 '13 at 20:58
  • Which "Install Other Frameworks" option are you talking about? .NET 4.5 *is* .NET 4.0 with some extra's they cannot be installed side-by-side like you think. It's the same withing with 2.0 and 3.0. 3.0 Would install 2.0 as well, no way around it. See: http://www.hanselman.com/blog/NETVersioningAndMultiTargetingNET45IsAnInplaceUpgradeToNET40.aspx – jessehouwing Jan 28 '13 at 21:02
  • Install Other Frameworks is visible in the Project page, tab Application, Target framework: .NET Framework 2.0, .NET Framework 3.0, .NET Framework 3.5, .NET Framework 4.5, Install Other Framework. When selecting the latter, I am redirected to http://msdn.microsoft.com/en-US/hh487283.aspx – Michel Keijzers Jan 28 '13 at 21:05
  • It *should* show 4.0 as well. See my screenshot. What project type are you using? – jessehouwing Jan 28 '13 at 21:15
  • I'm using C#, WPF (Windows Application). – Michel Keijzers Jan 28 '13 at 22:53
  • I tried didn't matter for me. Which exact Visual Studio version and edition are you using? – jessehouwing Jan 29 '13 at 01:11
  • I'm using VS Ultimate 2012, vwersion 11.0.5; I checked somewhere else ... and I think my install has not been completed correctly. I will try to reinstall it when I have more time but I'm sure it will then be ok. – Michel Keijzers Jan 29 '13 at 21:07
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    I reinstalled version 2010 and now 4.0 is added to the list again (also in 2012). – Michel Keijzers Jan 31 '13 at 09:16
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.NET Framework 4.5 is an in-place update and replaces .NET Framework 4. Once you install .NET Framework 4.5 there is no way to go back to .NET Framework 4. Note that major and minor versions of .NET Framework 4.5 assemblies were not changed. This means that a .NET Framework 4 app does not "see" a difference between the two and should run the same way. Since you want apps run on Windows XP you need to target .NET Framework 4 in your project. This will ensure that your app is not using any new APIs added in .NET Framework 4.5. After you do this you should be able to run your app on both .NET Framework 4 and .NET Framework 4.5. Note that even though the compatibility bar was very high (due to .NET Framework 4.5 being an in-place update) you will still find some minor differences (e.g. bugs that caused exceptions in .NET Framework 4 might have been fixed in .NET Framework 4.5 and exceptions are not throw anymore) and therefore you need to test your app on .NET Framework 4 machine thoroughly since running it on .NET Framework 4.5 will not reveal some issues. The reason for this is that targetting ensures that the app is not using APIs that did not exist before but cannot ensure the behavior at runtime since on the machine with .NET Framework 4.5 it will always use .NET Framework 4.5 runtime (since there is no .NET Framework 4 runtime there anymore).

Pawel
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    Thanks; however the main problem is that .NET Framework 4 cannot be selected anymore. And Windows XP does not run applications with .NET Framework 4.5. – Michel Keijzers Jan 29 '13 at 09:17
  • @MichelKeijzers what version of VS2012 are you using? Another thing to try is just to open the csproj file with notepad and change `v4.5` to `v4.0` – Pawel Jan 29 '13 at 16:59
  • I'm using VS Ultimate 2012, version 11.0.5 – Michel Keijzers Jan 29 '13 at 20:43
  • I tried changing all 4.5 references to 4.0 but when I open it it wants me to either download 4.0 (which does not work) or changing it to 4.5 again. – Michel Keijzers Jan 29 '13 at 20:43
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    i get this issue and I am running VS2015 – Kirsten Jan 07 '16 at 22:38
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    I ran into an issue where uninstalling VS2013 left my VS2015 in a state without the ability to target the 4.0 framework. Upon attempting to install 4.0, it said a later version was already installed. The solution for me was to do a "repair" of VS2015 (ii.e. go to add/remove programs, click vs2015 and select the repair option). This reinstalled whatever was necessary to target the 4.0 framework. – Derek Greer Mar 06 '16 at 02:50
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Simple, just check the control panel and uninstall the higher version and carry on with the installation.

Neel
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