diff --git a/Directory.Build.props b/Directory.Build.props
index 4d3e8a8408abf..4e86c1d212081 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -89,8 +89,9 @@
 
     <!-- The previous supported .NET version. -->
     <NetCoreAppPreviousVersion>8.0</NetCoreAppPreviousVersion>
-    <NetCoreAppPrevious>net$(NetCoreAppPreviousVersion)</NetCoreAppPrevious>
-    <NetCoreAppPrevious Condition="'$(DotNetBuildFromSource)' == 'true'">$(NetCoreAppCurrent)</NetCoreAppPrevious>
+    <!-- For the .NET 9 release, set NetCoreAppPrevious to empty as NuGet has issues
+         with duplicate TFMs (when using both NetCoreAppPrevious and NetCoreAppMinimum). -->
+    <NetCoreAppPrevious />
 
     <!-- The minimum supported .NET version. -->
     <NetCoreAppMinimum>net8.0</NetCoreAppMinimum>
diff --git a/src/libraries/Microsoft.Win32.Registry.AccessControl/src/Microsoft.Win32.Registry.AccessControl.csproj b/src/libraries/Microsoft.Win32.Registry.AccessControl/src/Microsoft.Win32.Registry.AccessControl.csproj
index 93bef46c41d5a..7c5c26f01d893 100644
--- a/src/libraries/Microsoft.Win32.Registry.AccessControl/src/Microsoft.Win32.Registry.AccessControl.csproj
+++ b/src/libraries/Microsoft.Win32.Registry.AccessControl/src/Microsoft.Win32.Registry.AccessControl.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <IsPartialFacadeAssembly>true</IsPartialFacadeAssembly>
     <IsPackable>true</IsPackable>
     <PackageDescription>Provides support for managing access and audit control lists for Microsoft.Win32.RegistryKey.
diff --git a/src/libraries/Microsoft.Win32.SystemEvents/src/Microsoft.Win32.SystemEvents.csproj b/src/libraries/Microsoft.Win32.SystemEvents/src/Microsoft.Win32.SystemEvents.csproj
index 8a6fa8533f9f0..e5586e668d250 100644
--- a/src/libraries/Microsoft.Win32.SystemEvents/src/Microsoft.Win32.SystemEvents.csproj
+++ b/src/libraries/Microsoft.Win32.SystemEvents/src/Microsoft.Win32.SystemEvents.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
     <PackageDescription>Provides access to Windows system event notifications.
diff --git a/src/libraries/System.Data.Odbc/src/System.Data.Odbc.csproj b/src/libraries/System.Data.Odbc/src/System.Data.Odbc.csproj
index 30399b2f3b692..f0030b42de013 100644
--- a/src/libraries/System.Data.Odbc/src/System.Data.Odbc.csproj
+++ b/src/libraries/System.Data.Odbc/src/System.Data.Odbc.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)-unix;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)-unix;netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)-unix;netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)-unix;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>$(NoWarn);CA2249;CA1838</NoWarn>
     <EnableAOTAnalyzer>false</EnableAOTAnalyzer>
diff --git a/src/libraries/System.Data.OleDb/src/System.Data.OleDb.csproj b/src/libraries/System.Data.OleDb/src/System.Data.OleDb.csproj
index bb549009216e3..8d4bee087440e 100644
--- a/src/libraries/System.Data.OleDb/src/System.Data.OleDb.csproj
+++ b/src/libraries/System.Data.OleDb/src/System.Data.OleDb.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <!-- Suppress CA2249: Consider using String.Contains instead of String.IndexOf to avoid ifdefs. -->
     <NoWarn>$(NoWarn);CA2249</NoWarn>
diff --git a/src/libraries/System.Diagnostics.EventLog/src/System.Diagnostics.EventLog.csproj b/src/libraries/System.Diagnostics.EventLog/src/System.Diagnostics.EventLog.csproj
index cc73f2a6daa4e..a03e6ca7e49f8 100644
--- a/src/libraries/System.Diagnostics.EventLog/src/System.Diagnostics.EventLog.csproj
+++ b/src/libraries/System.Diagnostics.EventLog/src/System.Diagnostics.EventLog.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
     <PackageDescription>Provides the System.Diagnostics.EventLog class, which allows the applications to use the Windows event log service.
diff --git a/src/libraries/System.Diagnostics.PerformanceCounter/src/System.Diagnostics.PerformanceCounter.csproj b/src/libraries/System.Diagnostics.PerformanceCounter/src/System.Diagnostics.PerformanceCounter.csproj
index c0435f2293bb1..93f9a48b7857a 100644
--- a/src/libraries/System.Diagnostics.PerformanceCounter/src/System.Diagnostics.PerformanceCounter.csproj
+++ b/src/libraries/System.Diagnostics.PerformanceCounter/src/System.Diagnostics.PerformanceCounter.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
     <PackageDescription>Provides the System.Diagnostics.PerformanceCounter class, which allows access to Windows performance counters.
diff --git a/src/libraries/System.DirectoryServices.AccountManagement/src/System.DirectoryServices.AccountManagement.csproj b/src/libraries/System.DirectoryServices.AccountManagement/src/System.DirectoryServices.AccountManagement.csproj
index ce36658a6eaac..0cced36afcebe 100644
--- a/src/libraries/System.DirectoryServices.AccountManagement/src/System.DirectoryServices.AccountManagement.csproj
+++ b/src/libraries/System.DirectoryServices.AccountManagement/src/System.DirectoryServices.AccountManagement.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
     <NoWarn>$(NoWarn);CA2249</NoWarn>
diff --git a/src/libraries/System.DirectoryServices.Protocols/src/System.DirectoryServices.Protocols.csproj b/src/libraries/System.DirectoryServices.Protocols/src/System.DirectoryServices.Protocols.csproj
index 11f18688ec399..5ba775da24ae5 100644
--- a/src/libraries/System.DirectoryServices.Protocols/src/System.DirectoryServices.Protocols.csproj
+++ b/src/libraries/System.DirectoryServices.Protocols/src/System.DirectoryServices.Protocols.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-osx;$(NetCoreAppCurrent)-linux;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)-osx;$(NetCoreAppPrevious)-linux;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)-osx;$(NetCoreAppMinimum)-linux;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-osx;$(NetCoreAppCurrent)-linux;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)-osx;$(NetCoreAppMinimum)-linux;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)-osx;$(NetCoreAppPrevious)-linux;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
     <IsPackable>true</IsPackable>
diff --git a/src/libraries/System.DirectoryServices/src/System.DirectoryServices.csproj b/src/libraries/System.DirectoryServices/src/System.DirectoryServices.csproj
index 943cc1bc374ec..8bd18417f83a2 100644
--- a/src/libraries/System.DirectoryServices/src/System.DirectoryServices.csproj
+++ b/src/libraries/System.DirectoryServices/src/System.DirectoryServices.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludeInternalObsoleteAttribute>true</IncludeInternalObsoleteAttribute>
     <NoWarn>$(NoWarn);IDE0059;IDE0060;CA1822</NoWarn>
diff --git a/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj b/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj
index 7ef8f91d1f6cc..b40713ebe5805 100644
--- a/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj
+++ b/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)-unix;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)-unix;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)-unix;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)-unix;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <DefineConstants>$(DefineConstants);SERIAL_PORTS</DefineConstants>
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
diff --git a/src/libraries/System.Management/src/System.Management.csproj b/src/libraries/System.Management/src/System.Management.csproj
index d07fdf39c2d0a..b68827d868adc 100644
--- a/src/libraries/System.Management/src/System.Management.csproj
+++ b/src/libraries/System.Management/src/System.Management.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>$(NoWarn);0618</NoWarn>
     <NoWarn>$(NoWarn);IDE0059;IDE0060;CA1822</NoWarn>
diff --git a/src/libraries/System.Net.Http.WinHttpHandler/src/System.Net.Http.WinHttpHandler.csproj b/src/libraries/System.Net.Http.WinHttpHandler/src/System.Net.Http.WinHttpHandler.csproj
index 4ae07fa2f55bc..1ba7ebc7eade7 100644
--- a/src/libraries/System.Net.Http.WinHttpHandler/src/System.Net.Http.WinHttpHandler.csproj
+++ b/src/libraries/System.Net.Http.WinHttpHandler/src/System.Net.Http.WinHttpHandler.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
diff --git a/src/libraries/System.Runtime.Caching/src/System.Runtime.Caching.csproj b/src/libraries/System.Runtime.Caching/src/System.Runtime.Caching.csproj
index b3d85127f0212..d0711461739bd 100644
--- a/src/libraries/System.Runtime.Caching/src/System.Runtime.Caching.csproj
+++ b/src/libraries/System.Runtime.Caching/src/System.Runtime.Caching.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
     <AddNETFrameworkPlaceholderFileToPackage>true</AddNETFrameworkPlaceholderFileToPackage>
diff --git a/src/libraries/System.Security.Cryptography.Pkcs/src/System.Security.Cryptography.Pkcs.csproj b/src/libraries/System.Security.Cryptography.Pkcs/src/System.Security.Cryptography.Pkcs.csproj
index a41d1dd716a21..19f34fd9101b7 100644
--- a/src/libraries/System.Security.Cryptography.Pkcs/src/System.Security.Cryptography.Pkcs.csproj
+++ b/src/libraries/System.Security.Cryptography.Pkcs/src/System.Security.Cryptography.Pkcs.csproj
@@ -1,8 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.1;netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
-	<DefineConstants>$(DefineConstants);BUILDING_PKCS</DefineConstants>
-	<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.1;netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
+    <DefineConstants>$(DefineConstants);BUILDING_PKCS</DefineConstants>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
     <NoWarn>$(NoWarn);CA5384</NoWarn>
     <IsPackable>true</IsPackable>
diff --git a/src/libraries/System.ServiceProcess.ServiceController/src/System.ServiceProcess.ServiceController.csproj b/src/libraries/System.ServiceProcess.ServiceController/src/System.ServiceProcess.ServiceController.csproj
index fec4052c5c037..a272f5bcb6d59 100644
--- a/src/libraries/System.ServiceProcess.ServiceController/src/System.ServiceProcess.ServiceController.csproj
+++ b/src/libraries/System.ServiceProcess.ServiceController/src/System.ServiceProcess.ServiceController.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>$(NoWarn);CA2249</NoWarn>
     <IsPackable>true</IsPackable>
diff --git a/src/libraries/System.Speech/src/System.Speech.csproj b/src/libraries/System.Speech/src/System.Speech.csproj
index 7369ceef1469a..a31c8c7408e69 100644
--- a/src/libraries/System.Speech/src/System.Speech.csproj
+++ b/src/libraries/System.Speech/src/System.Speech.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <!-- CS0649: uninitialized interop type fields -->
     <!-- SA1129: https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/3277 -->
diff --git a/src/libraries/System.Text.Encoding.CodePages/src/System.Text.Encoding.CodePages.csproj b/src/libraries/System.Text.Encoding.CodePages/src/System.Text.Encoding.CodePages.csproj
index 4635e3812e7c2..bbec0bfdfdf89 100644
--- a/src/libraries/System.Text.Encoding.CodePages/src/System.Text.Encoding.CodePages.csproj
+++ b/src/libraries/System.Text.Encoding.CodePages/src/System.Text.Encoding.CodePages.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
     <IsPackable>true</IsPackable>
diff --git a/src/libraries/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj b/src/libraries/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj
index 872bf0dc04d60..da6d7bb331ea5 100644
--- a/src/libraries/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj
+++ b/src/libraries/System.Text.Encodings.Web/src/System.Text.Encodings.Web.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-browser;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-browser;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-browser;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <!-- CS3011: Only CLS-compliant members can be abstract -->
     <!-- CS3019: CLS attributes on internal types. Some shared source files are internal in this project. -->
diff --git a/src/libraries/System.Threading.AccessControl/src/System.Threading.AccessControl.csproj b/src/libraries/System.Threading.AccessControl/src/System.Threading.AccessControl.csproj
index be657bede1ae4..8de54c2714b33 100644
--- a/src/libraries/System.Threading.AccessControl/src/System.Threading.AccessControl.csproj
+++ b/src/libraries/System.Threading.AccessControl/src/System.Threading.AccessControl.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
     <PackageDescription>Provides support for managing access and audit control lists for synchronization primitives.
diff --git a/src/libraries/System.Windows.Extensions/src/System.Windows.Extensions.csproj b/src/libraries/System.Windows.Extensions/src/System.Windows.Extensions.csproj
index 110d4511ade64..305383b1d512d 100644
--- a/src/libraries/System.Windows.Extensions/src/System.Windows.Extensions.csproj
+++ b/src/libraries/System.Windows.Extensions/src/System.Windows.Extensions.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum)</TargetFrameworks>
+    <TargetFrameworks Condition="'$(NetCoreAppPrevious)' != ''">$(TargetFrameworks);$(NetCoreAppPrevious)-windows;$(NetCoreAppPrevious)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <EnableAOTAnalyzer>false</EnableAOTAnalyzer>
     <IsPackable>true</IsPackable>