diff --git a/Make.versions b/Make.versions
index 9465808487..9d52198a35 100644
--- a/Make.versions
+++ b/Make.versions
@@ -142,4 +142,7 @@ SUPPORTED_API_VERSIONS_MACCATALYST=$(DOTNET_TFM)-$(MACCATALYST_NUGET_OS_VERSION)
 
 # Add older versions here!
 
-# (work on adding older versions is in progress)
+SUPPORTED_API_VERSIONS_IOS+=$(DOTNET_TFM)-17.0
+SUPPORTED_API_VERSIONS_TVOS+=$(DOTNET_TFM)-17.0
+SUPPORTED_API_VERSIONS_MACOS+=$(DOTNET_TFM)-14.0
+SUPPORTED_API_VERSIONS_MACCATALYST+=$(DOTNET_TFM)-17.0
diff --git a/docs/multi-target-framework.md b/docs/multi-target-framework.md
index 328e01ceef..052eb6edc4 100644
--- a/docs/multi-target-framework.md
+++ b/docs/multi-target-framework.md
@@ -122,39 +122,39 @@ WorkloadManifest.targets:
     <!-- Using a specific target platform version --> 
     <Import Project="Sdk.props"
         Sdk="Microsoft.iOS.Sdk.net7.0_16.0"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '16.0'))" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '16.0'))" />
     <Import Project="Sdk.props"
         Sdk="Microsoft.iOS.Sdk.net7.0_16.4"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '16.4'))" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '16.4'))" />
     <Import Project="Sdk.props"
         Sdk="Microsoft.iOS.Sdk.net8.0_17.0"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '8.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '17.0'))" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '8.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '17.0'))" />
     <Import Project="Sdk.props"
         Sdk="Microsoft.iOS.Sdk.net8.0_18.0"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '8.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '18.0'))" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '8.0')) And '$(TargetPlatformVersion)' != '' And $([MSBuild]::VersionEquals($(TargetPlatformVersion), '18.0'))" />
 
     <!-- Using the default target platform version -->
     <Import Project="Sdk.props"
         Sdk="Microsoft.iOS.Sdk.net7.0_16.4"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) And '$(TargetPlatformVersion)' == ''" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) And '$(TargetPlatformVersion)' == ''" />
     <Import Project="Sdk.props"
         Sdk="Microsoft.iOS.Sdk.net8.0_17.0"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '8.0')) And '$(TargetPlatformVersion)' == ''" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '8.0')) And '$(TargetPlatformVersion)' == ''" />
 
     <!-- Using a .NET version we no longer support -->
     <Import Project="Sdk-eol.props"
         Sdk="Microsoft.iOS.Sdk.net8.0_17.0"
-        Condition="'$(_AppleSdkLoaded)' != 'true' And $([MSBuild]::VersionLessThan($(TargetFrameworkVersion), '7.0'))" />
+        Condition="'$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionLessThan($(TargetFrameworkVersion), '7.0'))" />
 
     <!-- Using a specific, but unsupported, target platform version -->
     <Import Project="Sdk-error.props"
         Sdk="Microsoft.iOS.Sdk.net8.0_17.0"
-        Condition="'$(_AppleSdkLoaded)' != 'true'" />
+        Condition="'$(UsingAppleNETSdk)' != 'true'" />
 
 </ImportGroup>
 ```
 
-Note 1: Every sdk we load sets the property `_AppleSdkLoaded=true`, this makes
+Note 1: Every sdk we load sets the property `UsingAppleNETSdk=true`, this makes
 it easy to avoid loading multiple sdks.
 
 Note 2: One complication here is that TargetPlatformVersion might not be set
diff --git a/dotnet/Makefile b/dotnet/Makefile
index 3cd1152f83..36eaa46573 100644
--- a/dotnet/Makefile
+++ b/dotnet/Makefile
@@ -176,7 +176,7 @@ $(foreach platform,$(DOTNET_PLATFORMS),$(eval $(call SupportedTargetPlatforms,$(
 define WorkloadTargets
 Workloads/Microsoft.NET.Sdk.$(1)/WorkloadManifest.json: Makefile $(TOP)/Make.config.inc $(GIT_DIRECTORY)/HEAD $(GIT_DIRECTORY)/index Makefile generate-workloadmanifest-json.csharp | Workloads/Microsoft.NET.Sdk.$(1)
 	$$(Q) rm -f $$@.tmp
-	$$(Q_GEN) ./generate-workloadmanifest-json.csharp "$(1)" "$(3)" "$(5)" "$$(DOTNET_$(4)_RUNTIME_IDENTIFIERS)" "$$@.tmp" "$$(DOTNET_WINDOWS_PLATFORMS)" "$(DOTNET_TFM)_$$($(4)_NUGET_OS_VERSION)"
+	$$(Q_GEN) ./generate-workloadmanifest-json.csharp "$(1)" "$(3)" "$(5)" "$$(DOTNET_$(4)_RUNTIME_IDENTIFIERS)" "$$@.tmp" "$$(DOTNET_WINDOWS_PLATFORMS)" "$(DOTNET_TFM)_$$($(4)_NUGET_OS_VERSION)" "$(SUPPORTED_API_VERSIONS_$(4))" $(TOP)/eng/Versions.props
 	$$(Q) mv $$@.tmp $$@
 
 Workloads/Microsoft.NET.Sdk.$(1)/WorkloadManifest.targets: Makefile $(TOP)/Make.config.inc $(GIT_DIRECTORY)/HEAD $(GIT_DIRECTORY)/index Makefile generate-workloadmanifest-targets.csharp | Workloads/Microsoft.NET.Sdk.$(1)
diff --git a/dotnet/generate-workloadmanifest-json.csharp b/dotnet/generate-workloadmanifest-json.csharp
index 373958103a..c00901bac8 100755
--- a/dotnet/generate-workloadmanifest-json.csharp
+++ b/dotnet/generate-workloadmanifest-json.csharp
@@ -6,7 +6,7 @@ using System.IO;
 using System.Xml;
 
 var args = Args;
-var expectedArgumentCount = 7;
+var expectedArgumentCount = 9;
 if (args.Length != expectedArgumentCount) {
 	Console.WriteLine ($"Need {expectedArgumentCount} arguments, got {args.Length}");
 	Environment.Exit (1);
@@ -22,10 +22,25 @@ var outputPath = args [argumentIndex++];
 var windowsPlatforms = args [argumentIndex++].Split (new char [] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
 var hasWindows = Array.IndexOf (windowsPlatforms, platform) >= 0;
 var currentApiVersion = args [argumentIndex++];
+var supportedApiVersions = args [argumentIndex++].Split (new char [] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
+var versionsPropsPath = args [argumentIndex++];
 
 var platformLowerCase = platform.ToLowerInvariant ();
 
-var tfm = currentApiVersion;
+var allApiVersions = new List<string> (supportedApiVersions);
+allApiVersions = allApiVersions.Select (v => v.Replace ('-', '_')).ToList ();
+
+var versionsPropsTable = File.ReadAllLines (versionsPropsPath).
+				Where (v => v.Count (f => f == '>') > 1).
+				Select (v => {
+					var split = v.Trim ().Split (new char [] { '<', '>', '/'}, StringSplitOptions.RemoveEmptyEntries);
+					var name = split [0];
+					var value = split [1];
+					return new Tuple<string, string> (name, value);
+				}).
+				ToDictionary (v => v.Item1, v => v.Item2, StringComparer.OrdinalIgnoreCase);
+
+var failed = false;
 using (TextWriter writer = new StreamWriter (outputPath)) {
 	writer.WriteLine ($"{{");
 	writer.WriteLine ($"	\"version\": \"{version}\",");
@@ -39,9 +54,9 @@ using (TextWriter writer = new StreamWriter (outputPath)) {
 		writer.WriteLine ($"				\"Microsoft.{platform}.Windows.Sdk.Aliased.{tfm}\",");
 		writer.WriteLine ($"				\"Microsoft.{platform}.Windows.Sdk.Aliased.net8\",");
 	}
-	writer.WriteLine ($"				\"Microsoft.{platform}.Ref.{tfm}\",");
+	writer.WriteLine ($"				\"Microsoft.{platform}.Ref.{currentApiVersion}\",");
 	foreach (var rid in runtimeIdentifiers) {
-		writer.WriteLine ($"				\"Microsoft.{platform}.Runtime.{rid}.{tfm}\",");
+		writer.WriteLine ($"				\"Microsoft.{platform}.Runtime.{rid}.{currentApiVersion}\",");
 	}
 	writer.WriteLine ($"				\"Microsoft.{platform}.Templates.net9\"");
 	writer.WriteLine ($"			],");
@@ -62,6 +77,7 @@ using (TextWriter writer = new StreamWriter (outputPath)) {
 	writer.WriteLine ($"			\"version\": \"{version}\",");
 	writer.WriteLine ($"		}},");
 	writer.WriteLine ($"		\"Microsoft.{platform}.Sdk.net8\": {{");
+
 	writer.WriteLine ($"			\"kind\": \"sdk\",");
 	writer.WriteLine ($"			\"version\": \"{net8Version}\",");
 	writer.WriteLine ($"			\"alias-to\": {{");
@@ -88,12 +104,12 @@ using (TextWriter writer = new StreamWriter (outputPath)) {
 		writer.WriteLine ($"			}}");
 		writer.WriteLine ($"		}},");
 	}
-	writer.WriteLine ($"		\"Microsoft.{platform}.Ref.{tfm}\": {{");
+	writer.WriteLine ($"		\"Microsoft.{platform}.Ref.{currentApiVersion}\": {{");
 	writer.WriteLine ($"			\"kind\": \"framework\",");
 	writer.WriteLine ($"			\"version\": \"{version}\"");
 	writer.WriteLine ($"		}},");
 	foreach (var rid in runtimeIdentifiers) {
-		writer.WriteLine ($"		\"Microsoft.{platform}.Runtime.{rid}.{tfm}\": {{");
+		writer.WriteLine ($"		\"Microsoft.{platform}.Runtime.{rid}.{currentApiVersion}\": {{");
 		writer.WriteLine ($"			\"kind\": \"framework\",");
 		writer.WriteLine ($"			\"version\": \"{version}\"");
 		writer.WriteLine ($"		}},");
@@ -109,4 +125,6 @@ using (TextWriter writer = new StreamWriter (outputPath)) {
 	writer.WriteLine ($"}}");
 }
 
+if (failed)
+        Environment.Exit (1);
 Environment.Exit (0);
diff --git a/dotnet/generate-workloadmanifest-targets.csharp b/dotnet/generate-workloadmanifest-targets.csharp
index 896aa9e84f..ae1f05f27a 100755
--- a/dotnet/generate-workloadmanifest-targets.csharp
+++ b/dotnet/generate-workloadmanifest-targets.csharp
@@ -20,46 +20,53 @@ var windowsPlatforms = args [argumentIndex++].Split (new char [] { ' ' }, String
 var hasWindows = Array.IndexOf (windowsPlatforms, platform) >= 0;
 var currentApiVersion = args [argumentIndex++];
 var olderApiVersions = args [argumentIndex++];
-var defaultApiVersion = args [argumentIndex++];
+var supportedApiVersions = args [argumentIndex++];
 
 var platformLowerCase = platform.ToLowerInvariant ();
 var tfm = currentApiVersion;
 
 var supportedTFMs = new List<string> ();
-supportedTFMs.Add (currentApiVersion);
 supportedTFMs.AddRange (olderApiVersions.Split (' '));
+supportedTFMs.AddRange (supportedApiVersions.Split (' ').Select (v => v.Replace ('-', '_')));
+supportedTFMs.Sort ();
 
 var supportedTFVs = new List<string> ();
 
 using (var writer = new StreamWriter (outputPath)) {
 	writer.WriteLine ($"<Project>");
-	writer.WriteLine ($"	<ImportGroup Condition=\" '$(TargetPlatformIdentifier)' == '{platform}' \">");
 	foreach (var tfm in supportedTFMs) {
 		var tfv = tfm.Replace ("net", "");
 		var sep = tfv.IndexOfAny (new char [] { '-', '_' });
-		if (sep >= 0)
+		var tpv = "";
+		if (sep >= 0) {
+			tpv = tfv.Substring (sep + 1);
 			tfv = tfv.Substring (0, sep);
+		}
 		supportedTFVs.Add (tfv);
 		var workloadVersion = tfm;
 		if (tfv [0] == '7')
 			workloadVersion = tfm.Replace (".0", "");
-		writer.WriteLine ($"		<Import Project=\"Sdk.props\" Sdk=\"Microsoft.{platform}.Sdk.{workloadVersion}\" Condition=\" $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '{tfv}'))\" />");
-	}
-	if (hasWindows) {
-		writer.WriteLine ();
-		foreach (var tfm in supportedTFMs) {
-			var tfv = tfm.Replace ("net", "");
-			var sep = tfv.IndexOfAny (new char [] { '-', '_' });
-			if (sep >= 0)
-				tfv = tfv.Substring (0, tfv.IndexOfAny (new char [] { '-', '_' }));
-			var workloadVersion = tfm;
-			if (tfv [0] == '7')
-				workloadVersion = tfm.Replace (".0", "");
-			writer.WriteLine ($"		<Import Project=\"Sdk.props\" Sdk=\"Microsoft.{platform}.Windows.Sdk.Aliased.{workloadVersion}\" Condition=\" $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '{tfv}')) And $([MSBuild]::IsOSPlatform('windows'))\" />");
+		if (tfm == currentApiVersion) {
+			writer.WriteLine ($"	<ImportGroup Condition=\" '$(TargetPlatformIdentifier)' == '{platform}' And '$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '{tfv}'))\">");
+			writer.WriteLine ($"		<Import Project=\"Sdk.props\" Sdk=\"Microsoft.{platform}.Sdk.{workloadVersion}\" /> <!-- this SDK version will validate the TargetPlatformVersion and show an error (in .NET 9+) or a warning (.NET 8) if it's not valid -->");
+		} else if (tpv.Length > 0) {
+			writer.WriteLine ($"	<ImportGroup Condition=\" '$(TargetPlatformIdentifier)' == '{platform}' And '$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '{tfv}')) And '$(TargetPlatformVersion)' == '{tpv}'\">");
+			writer.WriteLine ($"		<Import Project=\"Sdk.props\" Sdk=\"Microsoft.{platform}.Sdk.{workloadVersion}\" />");
+		} else {
+			writer.WriteLine ($"	<ImportGroup Condition=\" '$(TargetPlatformIdentifier)' == '{platform}' And '$(UsingAppleNETSdk)' != 'true' And $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '{tfv}'))\">");
+			writer.WriteLine ($"		<Import Project=\"Sdk.props\" Sdk=\"Microsoft.{platform}.Sdk.{workloadVersion}\" />");
 		}
+
+		if (hasWindows) {
+			writer.WriteLine ($"		<Import Project=\"Sdk.props\" Sdk=\"Microsoft.{platform}.Windows.Sdk.Aliased.{workloadVersion}\" Condition=\" $([MSBuild]::IsOSPlatform('windows'))\" />");
+		}
+
+		writer.WriteLine ($"	</ImportGroup>");
+		writer.WriteLine ();
 	}
-	writer.WriteLine ();
+
 	var earliestSupportedTFV = supportedTFVs.Select (v => Version.Parse (v)).OrderBy (v => v).First ();
+	writer.WriteLine ($"	<ImportGroup Condition=\" '$(TargetPlatformIdentifier)' == '{platform}' And '$(UsingAppleNETSdk)' != 'true'\">");
 	writer.WriteLine ($"		<Import Project=\"Sdk-eol.props\" Sdk=\"Microsoft.{platform}.Sdk.{tfm}\" Condition=\" $([MSBuild]::VersionLessThan($(TargetFrameworkVersion), '{earliestSupportedTFV}'))\" />");
 	writer.WriteLine ($"	</ImportGroup>");
 	writer.WriteLine ();
diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 50adafa379..ced06e2dce 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -47,6 +47,23 @@
       <Uri>https://github.com/xamarin/xamarin-macios</Uri>
       <Sha>2cb9d6666fb84a59e149049f20fee18de0902129</Sha>
     </Dependency>
+    <!-- This is a subscription of the .NET 8/Xcode 15.0 versions of our packages -->
+    <Dependency Name="Microsoft.MacCatalyst.Sdk.net8.0_17.0" Version="17.0.8519">
+      <Uri>https://github.com/xamarin/xamarin-macios</Uri>
+      <Sha>492e53f5b423c6e9cbdb48f3d57c92a1f97b5005</Sha>
+    </Dependency>
+    <Dependency Name="Microsoft.macOS.Sdk.net8.0_17.0" Version="14.0.8519">
+      <Uri>https://github.com/xamarin/xamarin-macios</Uri>
+      <Sha>492e53f5b423c6e9cbdb48f3d57c92a1f97b5005</Sha>
+    </Dependency>
+    <Dependency Name="Microsoft.iOS.Sdk.net8.0_17.0" Version="17.0.8519">
+      <Uri>https://github.com/xamarin/xamarin-macios</Uri>
+      <Sha>492e53f5b423c6e9cbdb48f3d57c92a1f97b5005</Sha>
+    </Dependency>
+    <Dependency Name="Microsoft.tvOS.Sdk.net8.0_17.0" Version="17.0.8519">
+      <Uri>https://github.com/xamarin/xamarin-macios</Uri>
+      <Sha>492e53f5b423c6e9cbdb48f3d57c92a1f97b5005</Sha>
+    </Dependency>
     <Dependency Name="Microsoft.NET.Runtime.MonoTargets.Sdk" Version="9.0.0-alpha.1.23556.4">
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>cf47d9ff6827a3e1d6f2acbf925cd618418f20dd</Sha>
diff --git a/tests/dotnet/MultiTargetingLibrary/AppDelegate.cs b/tests/dotnet/MultiTargetingLibrary/AppDelegate.cs
index e6bb47853e..7f18721410 100644
--- a/tests/dotnet/MultiTargetingLibrary/AppDelegate.cs
+++ b/tests/dotnet/MultiTargetingLibrary/AppDelegate.cs
@@ -7,5 +7,10 @@ namespace MySimpleApp {
 		{
 			return 42;
 		}
+
+		public static Type GetNSObjectType ()
+		{
+			return typeof (Foundation.NSObject);
+		}
 	}
 }
diff --git a/tests/dotnet/UnitTests/PackTest.cs b/tests/dotnet/UnitTests/PackTest.cs
index 057e677814..ebc33c771f 100644
--- a/tests/dotnet/UnitTests/PackTest.cs
+++ b/tests/dotnet/UnitTests/PackTest.cs
@@ -176,7 +176,6 @@ namespace Xamarin.Tests {
 		[TestCase (ApplePlatform.iOS)]
 		[TestCase (ApplePlatform.TVOS)]
 		[TestCase (ApplePlatform.MacOSX)]
-		[Ignore ("Multi-targeting support has been temporarily reverted/postponed")]
 		public void MultiTargetLibraryProject (ApplePlatform platform)
 		{
 			Configuration.IgnoreIfIgnoredPlatform (platform);
diff --git a/tests/dotnet/UnitTests/ProjectTest.cs b/tests/dotnet/UnitTests/ProjectTest.cs
index ca09e8c894..2d50ac57d9 100644
--- a/tests/dotnet/UnitTests/ProjectTest.cs
+++ b/tests/dotnet/UnitTests/ProjectTest.cs
@@ -1517,7 +1517,6 @@ namespace Xamarin.Tests {
 		[TestCase (ApplePlatform.iOS)]
 		[TestCase (ApplePlatform.TVOS)]
 		[TestCase (ApplePlatform.MacOSX)]
-		[Ignore ("Multi-targeting support has been temporarily reverted/postponed")]
 		public void MultiTargetLibrary (ApplePlatform platform)
 		{
 			Configuration.IgnoreIfIgnoredPlatform (platform);
@@ -1620,6 +1619,7 @@ namespace Xamarin.Tests {
 			return supportedApiVersions
 				.Where (v => v.StartsWith (Configuration.DotNetTfm + "-", StringComparison.Ordinal))
 				.Select (v => v.Substring (Configuration.DotNetTfm.Length + 1))
+				.OrderBy (v => v)
 				.ToArray ();
 		}
 
diff --git a/tests/dotnet/UnitTests/TestBaseClass.cs b/tests/dotnet/UnitTests/TestBaseClass.cs
index e4ecb7b5e1..0b300666ca 100644
--- a/tests/dotnet/UnitTests/TestBaseClass.cs
+++ b/tests/dotnet/UnitTests/TestBaseClass.cs
@@ -441,8 +441,12 @@ namespace Xamarin.Tests {
 
 			var failures = new List<string> ();
 			for (var i = 0; i < expectedMessages.Length; i++) {
-				if (actualMessages [i].Message != expectedMessages [i]) {
-					failures.Add ($"\tUnexpected {type} message #{i}:\n\t\tExpected: {expectedMessages [i]}\n\t\tActual: {actualMessages [i].Message?.TrimEnd ()}");
+				var actual = actualMessages [i].Message ?? string.Empty;
+				var expected = expectedMessages [i];
+				if (actual != expected) {
+					actual = actual.Replace ("\n", "\\n").Replace ("\r", "\\r");
+					expected = expected.Replace ("\n", "\\n").Replace ("\r", "\\r");
+					failures.Add ($"\tUnexpected {type} message #{i}:\n\t\tExpected: {expected}\n\t\tActual:   {actual}");
 				}
 			}
 			if (!failures.Any ())