Environment.OSVersion returns the incorrect value for macOS 12 Monterey

[al-cheb]

[Environment]::OSVersion.Version.ToString() should return 12.0.0.

Current behavior:

PS > [Environment]::OSVersion

Platform ServicePack Version VersionString
-------- ----------- ------- -------------
    Unix             11.0.0  Unix 11.0.0

PS > sw_vers
ProductName:    macOS
ProductVersion: 12.0
BuildVersion:   21A5304g

PS >  sysctl -a| grep -e release -e version
user.posix2_version: 200112
kern.osrelease: 21.0.0
kern.version: Darwin Kernel Version 21.0.0: Mon Aug  2 00:18:11 PDT 2021; root:xnu-8019.30.9~9/RELEASE_X86_64
kern.posix1version: 200112
kern.osversion: 21A5304g
kern.iossupportversion: 15.0
kern.osproductversion: 12.0
kern.osproductversioncompat: 10.16
kern.osreleasetype: User
kern.system_version_compat: 0
vm.fault_resilient_media_release: 0
vm.shared_region_version: 3
net.inet.igmp.default_version: 3
net.inet.tcp.mptcp_preferred_version: 0
net.inet6.ip6.kame_version: 2009/apple-darwin
net.mpklog.version: 1
machdep.cpu.arch_perf.version: 1
machdep.cpu.microcode_version: 1070
security.mac.asp.active_rule_version: 10415043430518216312
security.mac.asp.stats.cache_release_count: 0

PS > dotnet --info
.NET SDK (reflecting any global.json):
 Version:   5.0.400
 Commit:    d61950f9bf

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  11.0
 OS Platform: Darwin
 RID:         osx-x64
 Base Path:   /Users/runner/.dotnet/sdk/5.0.400/

Host (useful for support):
  Version: 5.0.9
  Commit:  208e377a53

Expected value:

PS > [Environment]::OSVersion

Platform ServicePack Version VersionString
-------- ----------- ------- -------------
    Unix             12.0.0  Unix 12.0.0

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[KalleOlaviNiemitalo]

I guess it comes from

runtime/src/libraries/Common/src/Interop/OSX/Interop.libobjc.cs

Lines 54 to 61 in 208e377

	if (major == 10 && minor == 16)
	{
	// We get "compat" version for 11.0 unless we build with updated SDK.
	// Hopefully that will be before 11.x comes out
	// For now, this maps 10.16 to 11.0.
	major = 11;
	minor = 0;
	}

.

Does this mean the .NET Runtime is not yet built "with updated SDK"?

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

[Environment]::OSVersion.Version.ToString() should return 12.0.0.

Current behavior:

PS > [Environment]::OSVersion

Platform ServicePack Version VersionString
-------- ----------- ------- -------------
    Unix             11.0.0  Unix 11.0.0

PS > sw_vers
ProductName:    macOS
ProductVersion: 12.0
BuildVersion:   21A5304g

PS >  sysctl -a| grep -e release -e version
user.posix2_version: 200112
kern.osrelease: 21.0.0
kern.version: Darwin Kernel Version 21.0.0: Mon Aug  2 00:18:11 PDT 2021; root:xnu-8019.30.9~9/RELEASE_X86_64
kern.posix1version: 200112
kern.osversion: 21A5304g
kern.iossupportversion: 15.0
kern.osproductversion: 12.0
kern.osproductversioncompat: 10.16
kern.osreleasetype: User
kern.system_version_compat: 0
vm.fault_resilient_media_release: 0
vm.shared_region_version: 3
net.inet.igmp.default_version: 3
net.inet.tcp.mptcp_preferred_version: 0
net.inet6.ip6.kame_version: 2009/apple-darwin
net.mpklog.version: 1
machdep.cpu.arch_perf.version: 1
machdep.cpu.microcode_version: 1070
security.mac.asp.active_rule_version: 10415043430518216312
security.mac.asp.stats.cache_release_count: 0

PS > dotnet --info
.NET SDK (reflecting any global.json):
 Version:   5.0.400
 Commit:    d61950f9bf

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  11.0
 OS Platform: Darwin
 RID:         osx-x64
 Base Path:   /Users/runner/.dotnet/sdk/5.0.400/

Host (useful for support):
  Version: 5.0.9
  Commit:  208e377a53

Expected value:

PS > [Environment]::OSVersion

Platform ServicePack Version VersionString
-------- ----------- ------- -------------
    Unix             12.0.0  Unix 12.0.0

Author:	al-cheb
Assignees:	-
Labels:	area-System.Runtime, untriaged
Milestone:	6.0.0

[vcsjones]

I can't reproduce this in .NET 6, I think this is something that only applies to .NET 5 and 3.1.

Both the API and and dotnet --info are seem correct for 6.0 on my M1 Mac.

[vcsjones]

This is interesting - it seems that macOS freezes the version you get depending on what SDK you build it with. Based on the code above, it seems that it's getting 10.16 from the OS. It isn't "updating its lie" as 10.17 or similar.

If I tell macOS to not lie about the version, PowerShell starts working accordingly.

If what I said about the version being fixed based on the SDK, then #41012 may need to be revisited.

[chucker]

I guess it comes from

runtime/src/libraries/Common/src/Interop/OSX/Interop.libobjc.cs

Lines 54 to 61 in 208e377

	if (major == 10 && minor == 16)
	{
	// We get "compat" version for 11.0 unless we build with updated SDK.
	// Hopefully that will be before 11.x comes out
	// For now, this maps 10.16 to 11.0.
	major = 11;
	minor = 0;
	}

.
Does this mean the .NET Runtime is not yet built "with updated SDK"?

Can’t .NET simply set SYSTEM_VERSION_COMPAT = 0 and get rid of the above code altogether?

[wfurt]

Since this is global the real question is what else is impacted. I'll check if we can get the real version via sysctl. Also I'm not sure what is oldest version we need to support @danmoseley. Perhaps it is also time to update the SDK we use.

[wfurt]

I got VM up and @vcsjones was right. 6.0 works as expeced and return 12.0 as it it should. This is probably because we use updated SDK and OS does not lie to us.
So we should service 5.0 (and perhaps 3.1) @danmoseley but this should not impact 6.0 as far as I can tell.

[danmoseley]

Minimum supported versions are documented here

https://github.com/dotnet/core/blob/main/os-lifecycle-policy.md

6.0 : 10.14
3.1 and 5.0 : 10.13

Highest supported macOS versions are not documented there but historically I believe we have aimed for .NET versions still in support to support the latest released macOS as generally folks upgrade macOS eagerly. @leecow is that right?

[jeffhandley]

Moved to 7.0.0 milestone to reflect that this does not affect 6.0. Even though it also won't affect 7.0.0, we'll want to service 5.0 and possibly 3.1 for this if there's enough justification, so this will be on the radar during the 7.0.0 milestone.

[ghost]

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