1

I am looking to check compatibility impact for my .NET application. I need to target Windows 10. However, on Microsoft site, i could not find .NET framework 4.0 for Windows 10.

Do we don't have it for Windows 10 ? Is it not supported ? If yes, then what is the way ahead ?

Microsoft .NET Support

SimpleGuy
  • 2,764
  • 5
  • 28
  • 45
  • 2
    The .NET Framework is *backwards compatible*. This means you can install older versions on new windows versions. Sometimes, you can't install newer versions on *older* windows versions. This should work for you. I think Windows 10 even comes with .NET 4.6 OOTB, so you need not install anything for your app to work. – Yuval Itzchakov Oct 16 '15 at 07:54
  • AFAIK, Windows 10 should have .NET Framework 4.6 integrated and it should be backward compatible with 4.0, so you shouldn't have any problems. Though, best way to know is to test it. – LightBulb Oct 16 '15 at 07:56
  • @LightBulb Indeed, it should be and there shouldn't be any problems. I was actually looking for some text from Microsoft to prove a support for .NET 4.0 – SimpleGuy Oct 16 '15 at 08:10
  • 1
    .Net 4.6x is backwards compatible with all versions back to 4.0, but NOT with 3.5 which would have to be installed via "Programs and Features | Turn Windows Features on and off". However, see https://msdn.microsoft.com/en-us/library/ff602939%28v=vs.110%29.aspx for possible problems.... – Matthew Watson Oct 16 '15 at 08:24
  • Windows 10 has .NET 4.6 pre-installed. If you overwrite it with 4.0, assuming you could (you can't) then you'll destroy any program that depends on 4.5 and 4.6 features. Like the pre-installed Universal apps and many Store apps. If you need to test 4.0 then you'll need to use a virtual machine. Stop supporting XP, please. – Hans Passant Oct 16 '15 at 08:41
  • @HansPassant there is no need to explicity install any previous version from the 4.x branch as long as you have latest one installed. Only if you need 3.x support, you'd have to install it separately but there are known issues with it. So, OP should be able to test his application by simply running it (as long as his dependencies are .NET framework only) – LightBulb Oct 16 '15 at 08:48
  • 1
    Hmya, trusting that Microsoft gets this right is [not always warranted](http://stackoverflow.com/a/31774612/17034). – Hans Passant Oct 16 '15 at 08:54

2 Answers2

1

.NET 4.6 still uses CLR 4.0, thus any .NET 4.x code should work with no hassle.

Matías Fidemraizer
  • 63,804
  • 18
  • 124
  • 206
  • Thanks. Indeed it should work then. However, I was looking for some text from Microsoft to support the conclusion. Is there any ? – SimpleGuy Oct 16 '15 at 08:11
  • 1
    @SimpleGuy I believe that this "some text from Microsoft" doesn't exist, because .NET has been always backward compatible with some exceptions, but you should consider that if .NET 4.6 couldn't run 4.0 code, it would be a big capital letters and red warning when downloading .NET 4.6 or Visual Studio 2015, 2013 and 2012 would come with a big notice about "your 4.0 code base requires breaking changes"... – Matías Fidemraizer Oct 16 '15 at 08:24
1

The main confusion is there's really 2 important version numbers with any .NET version: the version number and the CLR version. An application actually cares less about the .NET version than it does the CLR version. Confusing? I agree. Let's talk more.

When .NET released, it was .NET 1.0 running on CLR 1.0. Nothing confusing about that. Soon after, .NET 1.1 released with CLR version 1.0. While for the most part you didn't need to rewrite code to go from one to the other, CLR 1.1 could not run code compiled for CLR 1.0 and vice versa. Still, that's not too confusing: a 1.0 app works only if you have 1.0, and a 1.1 app only if you have 1.1.

Then came .NET 2.0, and with it CLR 2.0. Again, CLR 2.0 was not backwards compatible so .NET 1.x apps could not run natively on it. Still clear, though now people were agitated they had to juggle 3 different huge installers. MS had a lot of plans for .NET in this period, so they changed how they deployed things and this is where it gets real fun, if your idea of "fun" is "difficult".

.NET 3.0 and .NET 3.5 released real close to each other. They both use CLR 2.0. If you had .NET 3.5 installed, because it used CLR 2.0, you could run any .NET 3.5, 3.0, or 2.0 application on it. But it couldn't run .NET 1.0 or .NET 1.1 applications, they required their repsective CLRs. Interestingly enough, you could compile an application targeting .NET 3.5 and run it on a machine with only .NET 2.0 installed, because they were compatible CLRs. You only got in trouble if you tried using libraries that were new in .NET 3.5, or the rare instances where they broke behavior.

.NET 4.0 released with CLR 4, I guess because they ran out of decimals for version numbers. Since it's not CLR 2, it couldn't really run applications configured for anything but .NET 4.0. But that's sort of a lie. You can use the "supportedRuntime" tag in your app.config to tell .NET that your application supports CLR 4. Since CLR 4 and CLR 2 are MOSTLY compatible in large ways, MOST .NET 2.0-3.x applications can run just fine on CLR 4. But it's not safe unless you verify you aren't relying on something that changed between the two, so they make you have to explicitly declare it as a desired feature. It's generally easier to just recompile your application for CLR 4, but mucking with the app.config is a good band-aid while you test and verify.

.NET 4.5, 4.5.1, 4.5.2, and 4.5.6 all run on CLR 4 and jeez that's a lot of versions.

In terms of what you can rely on, it's a mess. The 2.0 CLR is installed by default on Windows Vista and Windows 7, but it's 2.0 and 3.5 respectively. The 4.0 CLR is only available by default as of Windows 8 (ships with 4.5) and Windows 10 (ships with 4.6). Neither of these versions ship a 2.0 CLR, but I know 8 generally responded to attempts to run apps that needed it by offering to install it for you. This is confusing but until Vista shipped, you couldn't assume a client machine had any .NET framework and they all represented 500+MB downloads. So at least we're making progress.

General rules that have always held for .NET deployment since the 3.0 release: It's harder than you think. Always. It's easiest to deploy if you compile with whatever is the latest .NET framework, and often you don't need to update your code to make that happen. When you can't do that, it's easiest to deploy if you're running on whatever the latest CLR happens to be. It is currently 4. When you can't do that, sometimes your app will just work if you use app.config to force it onto the new CLR. Don't unleash this on customers without a lot of testing and verification first, or at least a warning that you're not 100% certain of it. If you aren't using .NET 4.x and can't rebuild for CLR 4 and can't use the config file to run, make sure your customers understand they need to install CLR 2, which is the .NET Framework 3.5. Keep your favorite beverage handy at your desk, always, if you are an installer developer.

ref: More in depth thread

Sizons
  • 640
  • 2
  • 8
  • 24