如果安装在安装了 .Net 4.6.2 的机器上，a.Net 4.6.1 将在哪个版本的 .Net 下运行？

Question

A couple of us are having a discussion, specifically about this fix that was released in.Net 4.6.2:

We fixed the 260 character (MAXPATH) file name length limitation in the System.IO APIs. Over 4500 of you voted for this issue on UserVoice!

source

We're getting this exception in an application that is installed on clients, around this problem. We do not control the.Net version installed on these clients though our installer specifies a minimum version,at least.Net 4.6.1 (soon to be upgraded).

So if our application is running as 4.6.1 we get this problem, if it's running as >4.6.2 we don't.

Our application targets the.Net 4.6.1, so I said we need to upgrade, as we're hitting this problem, a colleague said that:

anyone with a newer version of.Net wouldn't hit this problem

I said this is wrong, the assembly would still run as 4.6.1 not 4.6.2. I think I based this on a article I read some time ago by Scott Hansellman but this was specifically about older (pre 4.5 versions of.Net). So now I'm not sure if I'm correct or not:

In-place upgrade means that the CLR is the same but new libraries are added as well as bug fixes and performance improvements

So given an application that is compiled against 4.6.1 that accesses a long file path on a machine with.Net 4.6.2 installed would we get an exception or not?

Answer 1

From the offline installer download for .NET 4.6.2 (emphasis mine):

The Microsoft .NET Framework 4.6.2 is a highly compatible in-place update to the Microsoft .NET Framework 4, 4.5, 4.5.1, 4.5.2, 4.6, and 4.6.1.

The "in-place" part means that it effectively replaces the previous versions. At least, that's my understanding of it. So when you run a .NET 4.x application on a machine which has 4.6.2 (and nothing later) installed on it, it will run under 4.6.2.