diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 9c67b6ccb1f66..6617c4cd4c33b 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -374,13 +374,13 @@
       <Uri>https://github.com/dotnet/roslyn</Uri>
       <Sha>28e49407a6e4744819bd471707259b99964e441c</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.Analyzers" Version="3.11.0-beta1.24052.1">
+    <Dependency Name="Microsoft.CodeAnalysis.Analyzers" Version="3.11.0-beta1.24067.1">
       <Uri>https://github.com/dotnet/roslyn-analyzers</Uri>
-      <Sha>8a92037d28baf58560622cb4685ecefdc828c2c8</Sha>
+      <Sha>23ec029b47d68b1a80348c0dabc3bccf013c1fe6</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.NetAnalyzers" Version="9.0.0-preview.24052.1">
+    <Dependency Name="Microsoft.CodeAnalysis.NetAnalyzers" Version="9.0.0-preview.24067.1">
       <Uri>https://github.com/dotnet/roslyn-analyzers</Uri>
-      <Sha>8a92037d28baf58560622cb4685ecefdc828c2c8</Sha>
+      <Sha>23ec029b47d68b1a80348c0dabc3bccf013c1fe6</Sha>
     </Dependency>
     <Dependency Name="Microsoft.DotNet.ApiCompat.Task" Version="9.0.100-alpha.1.23551.3">
       <Uri>https://github.com/dotnet/sdk</Uri>
diff --git a/eng/Versions.props b/eng/Versions.props
index 290d0b0acb8da..0faa216df17ca 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -31,8 +31,8 @@
   </ItemGroup>
   <PropertyGroup>
     <!-- dotnet/roslyn-analyzers dependencies -->
-    <MicrosoftCodeAnalysisAnalyzersVersion>3.11.0-beta1.24052.1</MicrosoftCodeAnalysisAnalyzersVersion>
-    <MicrosoftCodeAnalysisNetAnalyzersVersion>9.0.0-preview.24052.1</MicrosoftCodeAnalysisNetAnalyzersVersion>
+    <MicrosoftCodeAnalysisAnalyzersVersion>3.11.0-beta1.24067.1</MicrosoftCodeAnalysisAnalyzersVersion>
+    <MicrosoftCodeAnalysisNetAnalyzersVersion>9.0.0-preview.24067.1</MicrosoftCodeAnalysisNetAnalyzersVersion>
     <!-- dotnet/roslyn dependencies -->
     <!--
       These versions should not be used by any project that contributes to the design-time experience in VS, such as an analyzer, code-fix, or generator assembly.
diff --git a/src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs b/src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs
index bd3134aa1c175..b2c1855ea44d8 100644
--- a/src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs
+++ b/src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs
@@ -522,7 +522,9 @@ private static Type CustomAttributeEncodingToType(CustomAttributeEncoding encode
             };
         }
 
+#pragma warning disable CA1859
         private static object EncodedValueToRawValue(long val, CustomAttributeEncoding encodedType)
+#pragma warning restore
         {
             switch (encodedType)
             {
diff --git a/src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/TypeSystem/RuntimeMethodDesc.cs b/src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/TypeSystem/RuntimeMethodDesc.cs
index c50958910212c..f95b8561e3a9d 100644
--- a/src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/TypeSystem/RuntimeMethodDesc.cs
+++ b/src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/TypeSystem/RuntimeMethodDesc.cs
@@ -63,7 +63,7 @@ public override Instantiation Instantiation
             }
         }
 
-        private TypeDesc _owningType;
+        private DefType _owningType;
         public override TypeDesc OwningType
         {
             get
diff --git a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Dataflow/MethodBodyScanner.cs b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Dataflow/MethodBodyScanner.cs
index 6e52bc778bcf4..13a55993c829e 100644
--- a/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Dataflow/MethodBodyScanner.cs
+++ b/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Dataflow/MethodBodyScanner.cs
@@ -123,8 +123,8 @@ private static Stack<StackSlot> MergeStack(Stack<StackSlot> a, Stack<StackSlot>
             }
 
             Stack<StackSlot> newStack = new Stack<StackSlot>(a.Count);
-            IEnumerator<StackSlot> aEnum = a.GetEnumerator();
-            IEnumerator<StackSlot> bEnum = b.GetEnumerator();
+            Stack<StackSlot>.Enumerator aEnum = a.GetEnumerator();
+            Stack<StackSlot>.Enumerator bEnum = b.GetEnumerator();
             while (aEnum.MoveNext() && bEnum.MoveNext())
             {
                 newStack.Push(MergeStackElement(aEnum.Current, bEnum.Current));
diff --git a/src/coreclr/tools/aot/ILCompiler.Compiler/ILCompiler.Compiler.csproj b/src/coreclr/tools/aot/ILCompiler.Compiler/ILCompiler.Compiler.csproj
index 6a35c1cc5c906..91276048b08e0 100644
--- a/src/coreclr/tools/aot/ILCompiler.Compiler/ILCompiler.Compiler.csproj
+++ b/src/coreclr/tools/aot/ILCompiler.Compiler/ILCompiler.Compiler.csproj
@@ -16,6 +16,7 @@
     <Configurations>Debug;Release;Checked</Configurations>
 
     <NoWarn Condition="'$(DotNetBuildFromSource)' == 'true'">$(NoWarn);CS8524</NoWarn>
+    <NoWarn>$(NoWarn);CA1859</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/coreclr/tools/aot/ILCompiler.RyuJit/JitInterface/CorInfoImpl.RyuJit.cs b/src/coreclr/tools/aot/ILCompiler.RyuJit/JitInterface/CorInfoImpl.RyuJit.cs
index e21640cbdbc24..4e2657c252cd5 100644
--- a/src/coreclr/tools/aot/ILCompiler.RyuJit/JitInterface/CorInfoImpl.RyuJit.cs
+++ b/src/coreclr/tools/aot/ILCompiler.RyuJit/JitInterface/CorInfoImpl.RyuJit.cs
@@ -823,7 +823,7 @@ private InfoAccessType constructStringLiteral(CORINFO_MODULE_STRUCT_* module, md
         {
             MethodIL methodIL = (MethodIL)HandleToObject((void*)module);
 
-            ISymbolNode stringObject;
+            FrozenStringNode stringObject;
             if (metaTok == (mdToken)CorConstants.CorTokenType.mdtString)
             {
                 stringObject = _compilation.NodeFactory.SerializedStringObject("");
@@ -1776,7 +1776,7 @@ private void embedGenericHandle(ref CORINFO_RESOLVED_TOKEN pResolvedToken, bool
         private CORINFO_METHOD_STRUCT_* embedMethodHandle(CORINFO_METHOD_STRUCT_* handle, ref void* ppIndirection)
         {
             MethodDesc method = HandleToObject(handle);
-            ISymbolNode methodHandleSymbol = _compilation.NodeFactory.RuntimeMethodHandle(method);
+            RuntimeMethodHandleNode methodHandleSymbol = _compilation.NodeFactory.RuntimeMethodHandle(method);
             CORINFO_METHOD_STRUCT_* result = (CORINFO_METHOD_STRUCT_*)ObjectToHandle(methodHandleSymbol);
 
             if (methodHandleSymbol.RepresentsIndirectionCell)
diff --git a/src/coreclr/tools/aot/ILCompiler.TypeSystem/ILCompiler.TypeSystem.csproj b/src/coreclr/tools/aot/ILCompiler.TypeSystem/ILCompiler.TypeSystem.csproj
index 38077dc40d581..c528fb3c67340 100644
--- a/src/coreclr/tools/aot/ILCompiler.TypeSystem/ILCompiler.TypeSystem.csproj
+++ b/src/coreclr/tools/aot/ILCompiler.TypeSystem/ILCompiler.TypeSystem.csproj
@@ -18,6 +18,7 @@
     <GenerateDependencyFile>false</GenerateDependencyFile>
     <Configurations>Debug;Release;Checked</Configurations>
     <IsTrimmable>true</IsTrimmable>
+    <NoWarn>$(NoWarn);CA1859</NoWarn>
   </PropertyGroup>
 
   <ItemGroup Label="Embedded Resources">
diff --git a/src/installer/managed/Microsoft.NET.HostModel/Bundle/Bundler.cs b/src/installer/managed/Microsoft.NET.HostModel/Bundle/Bundler.cs
index 47d7a350340af..a4333dabc45a1 100644
--- a/src/installer/managed/Microsoft.NET.HostModel/Bundle/Bundler.cs
+++ b/src/installer/managed/Microsoft.NET.HostModel/Bundle/Bundler.cs
@@ -91,7 +91,7 @@ private bool ShouldCompress(FileType type)
         /// startOffset: offset of the start 'file' within 'bundle'
         /// compressedSize: size of the compressed data, if entry was compressed, otherwise 0
         /// </returns>
-        private (long startOffset, long compressedSize) AddToBundle(Stream bundle, Stream file, FileType type)
+        private (long startOffset, long compressedSize) AddToBundle(Stream bundle, FileStream file, FileType type)
         {
             long startOffset = bundle.Position;
             if (ShouldCompress(type))
diff --git a/src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Parser.cs b/src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Parser.cs
index 038b71bef0759..3fe4357a26358 100644
--- a/src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Parser.cs
+++ b/src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Parser.cs
@@ -654,7 +654,7 @@ private bool IsBaseOrIdentity(ITypeSymbol source, ITypeSymbol dest)
             /// Finds the template arguments contained in the message string.
             /// </summary>
             /// <returns>A value indicating whether the extraction was successful.</returns>
-            private static bool ExtractTemplates(string? message, IDictionary<string, string> templateMap, List<string> templateList)
+            private static bool ExtractTemplates(string? message, Dictionary<string, string> templateMap, List<string> templateList)
             {
                 if (string.IsNullOrEmpty(message))
                 {
diff --git a/src/libraries/Microsoft.Extensions.Options/gen/Generator.cs b/src/libraries/Microsoft.Extensions.Options/gen/Generator.cs
index 02fb554ca0b48..48ac7eae83218 100644
--- a/src/libraries/Microsoft.Extensions.Options/gen/Generator.cs
+++ b/src/libraries/Microsoft.Extensions.Options/gen/Generator.cs
@@ -12,7 +12,9 @@
 
 namespace Microsoft.Extensions.Options.Generators
 {
+#pragma warning disable RS1041 // we're multi-targeting so this is fine
     [Generator]
+#pragma warning restore
     public class OptionsValidatorGenerator : IIncrementalGenerator
     {
         public void Initialize(IncrementalGeneratorInitializationContext context)
diff --git a/src/libraries/System.CodeDom/src/System/CodeDom/Compiler/CodeGeneratorOptions.cs b/src/libraries/System.CodeDom/src/System/CodeDom/Compiler/CodeGeneratorOptions.cs
index 86384a277f45f..bd31688bc15b1 100644
--- a/src/libraries/System.CodeDom/src/System/CodeDom/Compiler/CodeGeneratorOptions.cs
+++ b/src/libraries/System.CodeDom/src/System/CodeDom/Compiler/CodeGeneratorOptions.cs
@@ -8,7 +8,7 @@ namespace System.CodeDom.Compiler
 {
     public class CodeGeneratorOptions
     {
-        private readonly IDictionary _options = new ListDictionary();
+        private readonly ListDictionary _options = new ListDictionary();
 
         public CodeGeneratorOptions() { }
 
diff --git a/src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableExtensions.cs b/src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableExtensions.cs
index 08f32a5a70c53..823c5e04cd279 100644
--- a/src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableExtensions.cs
+++ b/src/libraries/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableExtensions.cs
@@ -175,7 +175,9 @@ private sealed class FallbackWrapper<T> : IOrderedCollection<T>
             /// <summary>
             /// The list-ified sequence.
             /// </summary>
+#pragma warning disable CA1859
             private IList<T>? _collection;
+#pragma warning restore
 
             /// <summary>
             /// Initializes a new instance of the <see cref="FallbackWrapper{T}"/> class.
diff --git a/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/PropertyDescriptorCollection.cs b/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/PropertyDescriptorCollection.cs
index 672a32ec8a597..e76ffff05bca7 100644
--- a/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/PropertyDescriptorCollection.cs
+++ b/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/PropertyDescriptorCollection.cs
@@ -18,7 +18,7 @@ public class PropertyDescriptorCollection : ICollection, IList, IDictionary
         /// </summary>
         public static readonly PropertyDescriptorCollection Empty = new PropertyDescriptorCollection(null, true);
 
-        private IDictionary? _cachedFoundProperties;
+        private Hashtable? _cachedFoundProperties;
         private bool _cachedIgnoreCase;
         private PropertyDescriptor[] _properties;
         private readonly string[]? _namedSort;
diff --git a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ClientSettingsStore.cs b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ClientSettingsStore.cs
index 9f5559ee2b82f..db8dacea39059 100644
--- a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ClientSettingsStore.cs
+++ b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ClientSettingsStore.cs
@@ -84,7 +84,7 @@ private static void DeclareSection(Configuration config, string sectionName)
 
         internal static IDictionary ReadSettings(string sectionName, bool isUserScoped)
         {
-            IDictionary settings = new Hashtable();
+            Hashtable settings = new Hashtable();
 
             if (isUserScoped && !ConfigurationManagerInternalFactory.Instance.SupportsUserConfig)
             {
@@ -108,7 +108,7 @@ internal static IDictionary ReadSettings(string sectionName, bool isUserScoped)
 
         internal static IDictionary ReadSettingsFromFile(string configFileName, string sectionName, bool isUserScoped)
         {
-            IDictionary settings = new Hashtable();
+            Hashtable settings = new Hashtable();
 
             if (isUserScoped && !ConfigurationManagerInternalFactory.Instance.SupportsUserConfig)
             {
diff --git a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ConfigurationElement.cs b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ConfigurationElement.cs
index 1dc0324e052f1..4f3d018622cb3 100644
--- a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ConfigurationElement.cs
+++ b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/ConfigurationElement.cs
@@ -1725,7 +1725,7 @@ private static object DeserializePropertyValue(ConfigurationProperty prop, XmlRe
                 // Validate the loaded and converted value
                 prop.Validate(propertyValue);
             }
-            catch (ConfigurationException ce)
+            catch (ConfigurationErrorsException ce)
             {
                 // If the error is incomplete - complete it :)
                 if (string.IsNullOrEmpty(ce.Filename)) ce = new ConfigurationErrorsException(ce.Message, reader);
diff --git a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/LocalFileSettingsProvider.cs b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/LocalFileSettingsProvider.cs
index 97534199e68dc..b2a2ee7085f08 100644
--- a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/LocalFileSettingsProvider.cs
+++ b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/LocalFileSettingsProvider.cs
@@ -149,8 +149,8 @@ public override SettingsPropertyValueCollection GetPropertyValues(SettingsContex
         public override void SetPropertyValues(SettingsContext context, SettingsPropertyValueCollection values)
         {
             string sectionName = GetSectionName(context);
-            IDictionary roamingUserSettings = new Hashtable();
-            IDictionary localUserSettings = new Hashtable();
+            Hashtable roamingUserSettings = new Hashtable();
+            Hashtable localUserSettings = new Hashtable();
 
             foreach (SettingsPropertyValue value in values)
             {
diff --git a/src/libraries/System.Data.Odbc/src/System/Data/Odbc/OdbcMetaDataFactory.cs b/src/libraries/System.Data.Odbc/src/System/Data/Odbc/OdbcMetaDataFactory.cs
index 50ebb7b59694c..9bfe41fa16ea9 100644
--- a/src/libraries/System.Data.Odbc/src/System/Data/Odbc/OdbcMetaDataFactory.cs
+++ b/src/libraries/System.Data.Odbc/src/System/Data/Odbc/OdbcMetaDataFactory.cs
@@ -134,7 +134,6 @@ internal OdbcMetaDataFactory(Stream XMLStream,
             }
         }
 
-#pragma warning disable CA1859 // https://github.com/dotnet/roslyn-analyzers/issues/6440
         private static object BooleanFromODBC(object odbcSource)
         {
             if (odbcSource != DBNull.Value)
@@ -154,7 +153,6 @@ private static object BooleanFromODBC(object odbcSource)
 
             return DBNull.Value;
         }
-#pragma warning disable CA1859
 
         private static OdbcCommand GetCommand(OdbcConnection connection)
         {
diff --git a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs
index 6bdba053407fd..dc10150408274 100644
--- a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs
+++ b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Collections.Specialized;
 using System.ComponentModel;
 using System.IO;
 using System.Runtime.InteropServices;
@@ -857,7 +858,7 @@ private static void CreatePipe(out SafeFileHandle parentHandle, out SafeFileHand
             }
         }
 
-        private static string GetEnvironmentVariablesBlock(IDictionary<string, string> sd)
+        private static string GetEnvironmentVariablesBlock(DictionaryWrapper sd)
         {
             // https://docs.microsoft.com/en-us/windows/win32/procthread/changing-environment-variables
             // "All strings in the environment block must be sorted alphabetically by name. The sort is
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/ActiveDirectorySchemaClass.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/ActiveDirectorySchemaClass.cs
index af7627cb068f7..9909ce6616036 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/ActiveDirectorySchemaClass.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/ActiveDirectorySchemaClass.cs
@@ -1268,7 +1268,7 @@ private void SetProperty(string propertyName, object? value)
         // This method searches in the schema container for all non-defunct classes of the
         // specified name (ldapDisplayName).
         //
-        private ArrayList GetClasses(ICollection ldapDisplayNames)
+        private ArrayList GetClasses(ArrayList ldapDisplayNames)
         {
             ArrayList classes = new ArrayList();
             SearchResultCollection? resCol = null;
@@ -1340,7 +1340,7 @@ private ArrayList GetClasses(ICollection ldapDisplayNames)
         // This method searches in the schema container for all non-defunct properties of the
         // specified name (ldapDisplayName).
         //
-        private ArrayList GetProperties(ICollection ldapDisplayNames)
+        private ArrayList GetProperties(ArrayList ldapDisplayNames)
         {
             ArrayList properties = new ArrayList();
             SearchResultCollection? resCol = null;
diff --git a/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/ExceptQueryOperator.cs b/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/ExceptQueryOperator.cs
index 0c86a0c18ca67..c0b2299430c8b 100644
--- a/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/ExceptQueryOperator.cs
+++ b/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/ExceptQueryOperator.cs
@@ -230,7 +230,9 @@ private sealed class OrderedExceptQueryOperatorEnumerator<TLeftKey> : QueryOpera
             private readonly QueryOperatorEnumerator<Pair<TInputOutput, NoKeyMemoizationRequired>, int> _rightSource; // Right data source.
             private readonly IEqualityComparer<TInputOutput>? _comparer; // A comparer used for equality checks/hash-coding.
             private readonly IComparer<TLeftKey> _leftKeyComparer; // A comparer for order keys.
+#pragma warning disable CA1859
             private IEnumerator<KeyValuePair<Wrapper<TInputOutput>, Pair<TInputOutput, TLeftKey>>>? _outputEnumerator; // The enumerator output elements + order keys.
+#pragma warning restore
             private readonly CancellationToken _cancellationToken;
 
             //---------------------------------------------------------------------------------------
diff --git a/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/UnionQueryOperator.cs b/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/UnionQueryOperator.cs
index 132e10dce0939..637e72f06787a 100644
--- a/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/UnionQueryOperator.cs
+++ b/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Binary/UnionQueryOperator.cs
@@ -294,7 +294,9 @@ private sealed class OrderedUnionQueryOperatorEnumerator<TLeftKey, TRightKey> :
             private readonly QueryOperatorEnumerator<Pair<TInputOutput, NoKeyMemoizationRequired>, TLeftKey> _leftSource; // Left data source.
             private readonly QueryOperatorEnumerator<Pair<TInputOutput, NoKeyMemoizationRequired>, TRightKey> _rightSource; // Right data source.
             private readonly IComparer<ConcatKey<TLeftKey, TRightKey>> _keyComparer; // Comparer for compound order keys.
+#pragma warning disable CA1859
             private IEnumerator<KeyValuePair<Wrapper<TInputOutput>, Pair<TInputOutput, ConcatKey<TLeftKey, TRightKey>>>>? _outputEnumerator; // Enumerator over the output of the union.
+#pragma warning restore
             private readonly bool _leftOrdered; // Whether the left data source is ordered.
             private readonly bool _rightOrdered; // Whether the right data source is ordered.
             private readonly IEqualityComparer<TInputOutput>? _comparer; // Comparer for the elements.
diff --git a/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Unary/DistinctQueryOperator.cs b/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Unary/DistinctQueryOperator.cs
index 50373196ebf98..8338d9f30e005 100644
--- a/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Unary/DistinctQueryOperator.cs
+++ b/src/libraries/System.Linq.Parallel/src/System/Linq/Parallel/QueryOperators/Unary/DistinctQueryOperator.cs
@@ -193,7 +193,9 @@ private sealed class OrderedDistinctQueryOperatorEnumerator<TKey> : QueryOperato
             private readonly QueryOperatorEnumerator<Pair<TInputOutput, NoKeyMemoizationRequired>, TKey> _source; // The data source.
             private readonly Dictionary<Wrapper<TInputOutput>, TKey> _hashLookup; // The hash lookup, used to produce the distinct set.
             private readonly IComparer<TKey> _keyComparer; // Comparer to decide the key order.
+#pragma warning disable CA1859
             private IEnumerator<KeyValuePair<Wrapper<TInputOutput>, TKey>>? _hashLookupEnumerator; // Enumerates over _hashLookup.
+#pragma warning restore
             private readonly CancellationToken _cancellationToken;
 
             //---------------------------------------------------------------------------------------
diff --git a/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs b/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs
index cee25b47fff61..942cd6ceaed36 100644
--- a/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs
+++ b/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs
@@ -212,6 +212,7 @@ private static TagList InitializeCommonTags(HttpRequestMessage request)
         private static object[]? s_boxedStatusCodes;
         private static string[]? s_statusCodeStrings;
 
+#pragma warning disable CA1859 // we explictly box here
         private static object GetBoxedStatusCode(int statusCode)
         {
             object[] boxes = LazyInitializer.EnsureInitialized(ref s_boxedStatusCodes, static () => new object[512]);
@@ -220,6 +221,7 @@ private static object GetBoxedStatusCode(int statusCode)
                 ? boxes[statusCode] ??= statusCode
                 : statusCode;
         }
+#pragma warning restore
 
         private static string GetErrorStatusCodeString(int statusCode)
         {
diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventProvider.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventProvider.cs
index e1fd28cc84b1b..0819e7096c862 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventProvider.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventProvider.cs
@@ -1346,7 +1346,7 @@ private static int FindNull(byte[] buffer, int idx)
 
         protected static unsafe IDictionary<string, string?>? ParseFilterData(byte[]? data)
         {
-            IDictionary<string, string?>? args = null;
+            Dictionary<string, string?>? args = null;
 
             // data can be null if the filterArgs had a very large size which failed our sanity check
             if (data != null)
diff --git a/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/DataContract.cs b/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/DataContract.cs
index 1028c02ff4c1a..bcf5c1064e31c 100644
--- a/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/DataContract.cs
+++ b/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/DataContract.cs
@@ -1482,7 +1482,7 @@ private static string GetDefaultXmlLocalName(Type type)
                 int iParam = typeName.IndexOf('[');
                 if (iParam >= 0)
                     typeName = typeName.Substring(0, iParam);
-                IList<int> nestedParamCounts = GetDataContractNameForGenericName(typeName, localName);
+                List<int> nestedParamCounts = GetDataContractNameForGenericName(typeName, localName);
                 bool isTypeOpenGeneric = type.IsGenericTypeDefinition;
                 Type[] genParams = type.GetGenericArguments();
                 for (int i = 0; i < genParams.Length; i++)
diff --git a/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/SchemaExporter.cs b/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/SchemaExporter.cs
index f0dd2508304ee..a6322854be790 100644
--- a/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/SchemaExporter.cs
+++ b/src/libraries/System.Private.DataContractSerialization/src/System/Runtime/Serialization/SchemaExporter.cs
@@ -263,7 +263,7 @@ private XmlElement ExportGenericInfo(Type clrType, string elementName, string el
             }
 
             Type[]? genericArguments = null;
-            IList<int>? genericArgumentCounts = null;
+            List<int>? genericArgumentCounts = null;
             if (clrType.IsGenericType)
             {
                 genericArguments = clrType.GetGenericArguments();
diff --git a/src/libraries/System.Private.Xml/src/System/Xml/Serialization/Compilation.cs b/src/libraries/System.Private.Xml/src/System/Xml/Serialization/Compilation.cs
index d715b22419293..d8099a5b4e1f3 100644
--- a/src/libraries/System.Private.Xml/src/System/Xml/Serialization/Compilation.cs
+++ b/src/libraries/System.Private.Xml/src/System/Xml/Serialization/Compilation.cs
@@ -21,8 +21,8 @@ internal sealed class TempAssembly
         internal const string GeneratedAssemblyNamespace = "Microsoft.Xml.Serialization.GeneratedAssembly";
         private readonly Assembly? _assembly;
         private XmlSerializerImplementation? _contract;
-        private IDictionary? _writerMethods;
-        private IDictionary? _readerMethods;
+        private Hashtable? _writerMethods;
+        private Hashtable? _readerMethods;
         private TempMethodDictionary? _methods;
 
         internal sealed class TempMethod
diff --git a/src/libraries/System.Private.Xml/src/System/Xml/Xsl/Xslt/QilGenerator.cs b/src/libraries/System.Private.Xml/src/System/Xml/Xsl/Xslt/QilGenerator.cs
index dab9de5704321..4b7a35946a286 100644
--- a/src/libraries/System.Private.Xml/src/System/Xml/Xsl/Xslt/QilGenerator.cs
+++ b/src/libraries/System.Private.Xml/src/System/Xml/Xsl/Xslt/QilGenerator.cs
@@ -2563,7 +2563,7 @@ private static void SetArg(IList<XslNode> args, int pos, QilName name, QilNode v
         // Returns true if formalArgs maps 1:1 with actual args.
         // Formally this is n*n algorithm. We can optimize it by calculationg "signature"
         // of the function as sum of all hashes of its args names.
-        private static bool FillupInvokeArgs(IList<QilNode> formalArgs, IList<XslNode> actualArgs, QilList invokeArgs)
+        private static bool FillupInvokeArgs(QilList formalArgs, IList<XslNode> actualArgs, QilList invokeArgs)
         {
             if (actualArgs.Count != formalArgs.Count)
             {
diff --git a/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs b/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs
index acc214efb54ad..28afdac864052 100644
--- a/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs
+++ b/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs
@@ -899,7 +899,7 @@ private static bool NeedsExplicitNamespace(string dataContractNamespace, string
             if (knownTypeDictionary == null)
                 return null;
 
-            ICollection<DataContract>? knownTypeContracts = knownTypeDictionary.Values;
+            DataContractDictionary.ValueCollection? knownTypeContracts = knownTypeDictionary.Values;
             if (knownTypeContracts == null || knownTypeContracts.Count == 0)
                 return null;
 
diff --git a/src/libraries/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/Windows/DecryptorPalWindows.DecodeRecipients.cs b/src/libraries/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/Windows/DecryptorPalWindows.DecodeRecipients.cs
index 27a48486adf4e..a9233e64dacee 100644
--- a/src/libraries/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/Windows/DecryptorPalWindows.DecodeRecipients.cs
+++ b/src/libraries/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/Windows/DecryptorPalWindows.DecodeRecipients.cs
@@ -33,9 +33,7 @@ private static RecipientInfoCollection CreateRecipientInfos(SafeCryptMsgHandle h
             return new RecipientInfoCollection(recipientInfos);
         }
 
-#pragma warning disable CA1859 // Use concrete types when possible for improved performance https://github.com/dotnet/roslyn-analyzers/issues/6751
         private static IEnumerable<RecipientInfo> ToRecipientInfosForThisIndex(SafeHandle pCmsgCmsRecipientInfoMemory, int index)
-#pragma warning restore CA1859
         {
             bool mustRelease = false;
             pCmsgCmsRecipientInfoMemory.DangerousAddRef(ref mustRelease);
diff --git a/src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/ChainPal.Apple.cs b/src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/ChainPal.Apple.cs
index 6df9aacc72785..6504190da1d20 100644
--- a/src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/ChainPal.Apple.cs
+++ b/src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/ChainPal.Apple.cs
@@ -190,7 +190,7 @@ private SafeCreateHandle PrepareCustomCertsArray(X509Certificate2Collection cust
             return GetCertsArray(rootCertificates);
         }
 
-        private SafeCreateHandle GetCertsArray(IList<SafeHandle> safeHandles)
+        private SafeCreateHandle GetCertsArray(List<SafeHandle> safeHandles)
         {
             int idx = 0;
 
diff --git a/src/libraries/System.Speech/src/Internal/SrgsCompiler/BackEnd.cs b/src/libraries/System.Speech/src/Internal/SrgsCompiler/BackEnd.cs
index 308e880053eaf..f6cb21d392847 100644
--- a/src/libraries/System.Speech/src/Internal/SrgsCompiler/BackEnd.cs
+++ b/src/libraries/System.Speech/src/Internal/SrgsCompiler/BackEnd.cs
@@ -819,7 +819,7 @@ internal void InitFromBinaryGrammar(StreamMarshaler streamHelper)
             bool fLastArcNull = true;
             CfgArc pLastArc = new();
             State currentState = null;
-            IEnumerator<KeyValuePair<int, Rule>> ieFirstArcs = ruleFirstArcs.GetEnumerator();
+            SortedDictionary<int, Rule>.Enumerator ieFirstArcs = ruleFirstArcs.GetEnumerator();
 
             // If no rules, then we have no arcs
             if (ieFirstArcs.MoveNext())
diff --git a/src/libraries/System.Speech/src/Recognition/SrgsGrammar/SrgsGrammarCompiler.cs b/src/libraries/System.Speech/src/Recognition/SrgsGrammar/SrgsGrammarCompiler.cs
index 5c01d78a57867..8418c2fe9019a 100644
--- a/src/libraries/System.Speech/src/Recognition/SrgsGrammar/SrgsGrammarCompiler.cs
+++ b/src/libraries/System.Speech/src/Recognition/SrgsGrammar/SrgsGrammarCompiler.cs
@@ -115,7 +115,7 @@ public static void CompileClassLibrary(XmlReader reader, string outputPath, stri
         // Decide if the input stream is a cfg.
         // If not assume it's an xml grammar.
         // The stream parameter points to the start of the data on entry and is reset to that point on exit.
-        private static bool CheckIfCfg(Stream stream, out int cfgLength)
+        private static bool CheckIfCfg(SeekableReadStream stream, out int cfgLength)
         {
             long initialPosition = stream.Position;
 
diff --git a/src/libraries/System.Speech/src/Result/SemanticValue.cs b/src/libraries/System.Speech/src/Result/SemanticValue.cs
index 10a44f8dadd92..7f03ed9b79330 100644
--- a/src/libraries/System.Speech/src/Result/SemanticValue.cs
+++ b/src/libraries/System.Speech/src/Result/SemanticValue.cs
@@ -257,7 +257,7 @@ public SemanticValue[] AKeys
             private object _name;
             private object _value;
             private float _confidence;
-            private IDictionary<string, SemanticValue> _dictionary;
+            private Dictionary<string, SemanticValue> _dictionary;
         }
 
         #endregion
diff --git a/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Roslyn4.0.cs b/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Roslyn4.0.cs
index 447f54c7f0782..069429b592fe0 100644
--- a/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Roslyn4.0.cs
+++ b/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Roslyn4.0.cs
@@ -16,7 +16,9 @@ namespace System.Text.Json.SourceGeneration
     /// <summary>
     /// Generates source code to optimize serialization and deserialization with JsonSerializer.
     /// </summary>
+#pragma warning disable RS1041 // we're multi-targeting so this is fine
     [Generator]
+#pragma warning restore
     public sealed partial class JsonSourceGenerator : IIncrementalGenerator
     {
 #if ROSLYN4_4_OR_GREATER
diff --git a/src/mono/browser/debugger/BrowserDebugProxy/MemberObjectsExplorer.cs b/src/mono/browser/debugger/BrowserDebugProxy/MemberObjectsExplorer.cs
index 1b173c3348234..ff3321e7abf4e 100644
--- a/src/mono/browser/debugger/BrowserDebugProxy/MemberObjectsExplorer.cs
+++ b/src/mono/browser/debugger/BrowserDebugProxy/MemberObjectsExplorer.cs
@@ -573,7 +573,7 @@ public static async Task<GetMembersResult> GetObjectMemberValues(
                 // 0th id is for the object itself, and then its ancestors
                 bool isOwn = i == 0;
 
-                IReadOnlyList<FieldTypeClass> thisTypeFields = await sdbHelper.GetTypeFields(typeId, token);
+                List<FieldTypeClass> thisTypeFields = await sdbHelper.GetTypeFields(typeId, token);
                 if (!includeStatic)
                     thisTypeFields = thisTypeFields.Where(f => !f.Attributes.HasFlag(FieldAttributes.Static)).ToList();
 
diff --git a/src/tasks/AotCompilerTask/MonoAOTCompiler.cs b/src/tasks/AotCompilerTask/MonoAOTCompiler.cs
index 32cc55e3e126c..09d58b2a9d083 100644
--- a/src/tasks/AotCompilerTask/MonoAOTCompiler.cs
+++ b/src/tasks/AotCompilerTask/MonoAOTCompiler.cs
@@ -293,7 +293,7 @@ public class MonoAOTCompiler : Microsoft.Build.Utilities.Task
 
     private List<string> _fileWrites = new();
 
-    private IList<ITaskItem>? _assembliesToCompile;
+    private List<ITaskItem>? _assembliesToCompile;
     private ConcurrentDictionary<string, ITaskItem> compiledAssemblies = new();
     private BuildPropertiesTable? _propertiesTable;
 
@@ -1200,7 +1200,7 @@ private bool TryGetAssemblyName(string asmPath, [NotNullWhen(true)] out string?
         }
     }
 
-    private void CheckExportSymbolsFile(IList<ITaskItem> assemblies)
+    private void CheckExportSymbolsFile(List<ITaskItem> assemblies)
     {
         if (!EnableUnmanagedCallersOnlyMethodsExport)
             return;
@@ -1215,7 +1215,7 @@ private void CheckExportSymbolsFile(IList<ITaskItem> assemblies)
         }
     }
 
-    private static List<ITaskItem> ConvertAssembliesDictToOrderedList(ConcurrentDictionary<string, ITaskItem> dict, IList<ITaskItem> originalAssemblies)
+    private static List<ITaskItem> ConvertAssembliesDictToOrderedList(ConcurrentDictionary<string, ITaskItem> dict, List<ITaskItem> originalAssemblies)
     {
         List<ITaskItem> outItems = new(originalAssemblies.Count);
         foreach (ITaskItem item in originalAssemblies)
diff --git a/src/tasks/MonoTargetsTasks/ILStrip/ILStrip.cs b/src/tasks/MonoTargetsTasks/ILStrip/ILStrip.cs
index 6a25bd26168b9..88cf91506e299 100644
--- a/src/tasks/MonoTargetsTasks/ILStrip/ILStrip.cs
+++ b/src/tasks/MonoTargetsTasks/ILStrip/ILStrip.cs
@@ -219,9 +219,9 @@ private static string ComputeTrimmedAssemblyPath(string trimmedAssemblyFolder, s
     private static bool IsInputNewerThanOutput(string inFile, string outFile)
         => File.GetLastWriteTimeUtc(inFile) > File.GetLastWriteTimeUtc(outFile);
 
-    private static List<ITaskItem> ConvertAssembliesDictToOrderedList(ConcurrentDictionary<string, ITaskItem> dict, IList<ITaskItem> originalAssemblies)
+    private static List<ITaskItem> ConvertAssembliesDictToOrderedList(ConcurrentDictionary<string, ITaskItem> dict, ITaskItem[] originalAssemblies)
     {
-        List<ITaskItem> outItems = new(originalAssemblies.Count);
+        List<ITaskItem> outItems = new(originalAssemblies.Length);
         foreach (ITaskItem item in originalAssemblies)
         {
             if (dict.TryGetValue(item.GetMetadata("FullPath"), out ITaskItem? dictItem))
diff --git a/src/tasks/WorkloadBuildTasks/PackageInstaller.cs b/src/tasks/WorkloadBuildTasks/PackageInstaller.cs
index d5646a399ef87..391c650f82892 100644
--- a/src/tasks/WorkloadBuildTasks/PackageInstaller.cs
+++ b/src/tasks/WorkloadBuildTasks/PackageInstaller.cs
@@ -69,7 +69,7 @@ private bool InstallActual(PackageReference[] references, bool stopOnMissing)
                 return false;
             }
 
-            IList<(PackageReference, string)> failedToRestore = references
+            List<(PackageReference, string)> failedToRestore = references
                                                              .Select(r => (r, Path.Combine(_packagesDir, r.Name.ToLowerInvariant(), r.Version)))
                                                              .Where(tuple => !Directory.Exists(tuple.Item2))
                                                              .ToList();
diff --git a/src/tools/illink/src/ILLink.Tasks/CreateRuntimeRootDescriptorFile.cs b/src/tools/illink/src/ILLink.Tasks/CreateRuntimeRootDescriptorFile.cs
index 8efb5ee3db398..16544bf8a7986 100644
--- a/src/tools/illink/src/ILLink.Tasks/CreateRuntimeRootDescriptorFile.cs
+++ b/src/tools/illink/src/ILLink.Tasks/CreateRuntimeRootDescriptorFile.cs
@@ -314,7 +314,7 @@ void OutputXml (string iLLinkTrimXmlFilePath, string outputFileName)
 						continue;
 
 					// <assembly fullname="System.Private.CoreLib" feature="System.Diagnostics.Tracing.EventSource.IsSupported" featurevalue="true" featuredefault="true">
-					XmlNode featureAssemblyNode = doc.CreateElement ("assembly");
+					XmlElement featureAssemblyNode = doc.CreateElement ("assembly");
 					XmlAttribute featureAssemblyFullName = doc.CreateAttribute ("fullname");
 					featureAssemblyFullName.Value = "System.Private.CoreLib";
 					featureAssemblyNode.Attributes.Append (featureAssemblyFullName);
@@ -369,7 +369,7 @@ static void AddXmlTypeNode (XmlDocument doc, XmlNode assemblyNode, string typeNa
 
 				if (!members.keepAllFields && (members.fields != null)) {
 					foreach (string field in members.fields) {
-						XmlNode fieldNode = doc.CreateElement ("field");
+						XmlElement fieldNode = doc.CreateElement ("field");
 						XmlAttribute fieldName = doc.CreateAttribute ("name");
 						fieldName.Value = field;
 						fieldNode.Attributes.Append (fieldName);
@@ -379,7 +379,7 @@ static void AddXmlTypeNode (XmlDocument doc, XmlNode assemblyNode, string typeNa
 
 				if (members.methods != null) {
 					foreach (string method in members.methods) {
-						XmlNode methodNode = doc.CreateElement ("method");
+						XmlElement methodNode = doc.CreateElement ("method");
 						XmlAttribute methodName = doc.CreateAttribute ("name");
 						methodName.Value = method;
 						methodNode.Attributes.Append (methodName);
diff --git a/src/tools/illink/src/analyzer/LinkerAnalyzerCore/SpaceAnalyzer.cs b/src/tools/illink/src/analyzer/LinkerAnalyzerCore/SpaceAnalyzer.cs
index 9d0d8577aa9a9..b77fcd1c80baf 100644
--- a/src/tools/illink/src/analyzer/LinkerAnalyzerCore/SpaceAnalyzer.cs
+++ b/src/tools/illink/src/analyzer/LinkerAnalyzerCore/SpaceAnalyzer.cs
@@ -68,9 +68,9 @@ static string GetTypeKey (TypeDefinition td)
 			return $"{td.MetadataToken.TokenType}:{td}{addition}";
 		}
 
-		static string GetKey (IMetadataTokenProvider provider)
+		static string GetKey (MethodDefinition method)
 		{
-			return $"{provider.MetadataToken.TokenType}:{provider}";
+			return $"{method.MetadataToken.TokenType}:{method}";
 		}
 
 		int GetMethodSize (MethodDefinition method)
diff --git a/src/tools/illink/src/linker/Linker.Dataflow/MethodBodyScanner.cs b/src/tools/illink/src/linker/Linker.Dataflow/MethodBodyScanner.cs
index 0ed295ecf4681..4d4855dc7ce6d 100644
--- a/src/tools/illink/src/linker/Linker.Dataflow/MethodBodyScanner.cs
+++ b/src/tools/illink/src/linker/Linker.Dataflow/MethodBodyScanner.cs
@@ -116,8 +116,8 @@ private static Stack<StackSlot> MergeStack (Stack<StackSlot> a, Stack<StackSlot>
 			}
 
 			Stack<StackSlot> newStack = new Stack<StackSlot> (a.Count);
-			IEnumerator<StackSlot> aEnum = a.GetEnumerator ();
-			IEnumerator<StackSlot> bEnum = b.GetEnumerator ();
+			Stack<StackSlot>.Enumerator aEnum = a.GetEnumerator ();
+			Stack<StackSlot>.Enumerator bEnum = b.GetEnumerator ();
 			while (aEnum.MoveNext () && bEnum.MoveNext ()) {
 				newStack.Push (MergeStackElement (aEnum.Current, bEnum.Current));
 			}