diff --git a/eng/Versions.props b/eng/Versions.props
index bba3a3f37d..df01f21c29 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -12,7 +12,7 @@
     -->
     <StabilizePackageVersion Condition="'$(StabilizePackageVersion)' == ''">false</StabilizePackageVersion>
     <DotNetFinalVersionKind Condition="'$(StabilizePackageVersion)' == 'true'">release</DotNetFinalVersionKind>
-    <DefaultNetCoreTargetFramework>net9.0</DefaultNetCoreTargetFramework>
+    <DefaultNetCoreTargetFramework>net10.0</DefaultNetCoreTargetFramework>
   </PropertyGroup>
   <PropertyGroup Label="Dependencies from nuget.org">
     <MicrosoftBuildFrameworkVersion>16.0.461</MicrosoftBuildFrameworkVersion>
diff --git a/src/EntityFramework/Core/Objects/ELinq/LinqExpressionNormalizer.cs b/src/EntityFramework/Core/Objects/ELinq/LinqExpressionNormalizer.cs
index 680c2499fc..3e08a4d8b8 100644
--- a/src/EntityFramework/Core/Objects/ELinq/LinqExpressionNormalizer.cs
+++ b/src/EntityFramework/Core/Objects/ELinq/LinqExpressionNormalizer.cs
@@ -7,6 +7,7 @@ namespace System.Data.Entity.Core.Objects.ELinq
     using System.Data.Entity.Utilities;
     using System.Diagnostics;
     using System.Diagnostics.CodeAnalysis;
+    using System.Linq;
     using System.Linq.Expressions;
     using System.Reflection;
 
@@ -38,6 +39,20 @@ internal class LinqExpressionNormalizer : EntityExpressionVisitor
         // </summary>
         private readonly Dictionary<Expression, Pattern> _patterns = new Dictionary<Expression, Pattern>();
 
+#if NETSTANDARD2_1
+        // Cache for Enumerable.Contains method lookup to avoid repeated reflection
+        private static readonly Lazy<MethodInfo> _enumerableContainsMethod = new Lazy<MethodInfo>(() =>
+            typeof(System.Linq.Enumerable).GetMethods()
+                .Where(method => method.Name == nameof(Enumerable.Contains) && method.GetParameters().Length == 2)
+                .Single());
+
+        // Cache for Enumerable.SequenceEqual method lookup to avoid repeated reflection
+        private static readonly Lazy<MethodInfo> _enumerableSequenceEqualMethod = new Lazy<MethodInfo>(() =>
+            typeof(System.Linq.Enumerable).GetMethods()
+                .Where(method => method.Name == nameof(Enumerable.SequenceEqual) && method.GetParameters().Length == 2)
+                .Single());
+#endif
+
         // <summary>
         // Handle binary patterns:
         // - VB 'Is' operator
@@ -124,6 +139,32 @@ private static bool IsConstantZero(Expression expression)
                    ((ConstantExpression)expression).Value.Equals(0);
         }
 
+#if NETSTANDARD2_1
+        // <summary>
+        // Attempts to unwrap an implicit Span or ReadOnlySpan cast expression to get the underlying array or collection.
+        // This is used to rewrite MemoryExtensions methods that operate on Span/ReadOnlySpan back to Enumerable methods.
+        // </summary>
+        private static bool TryUnwrapSpanImplicitCast(Expression expression, out Expression result)
+        {
+            if (expression is MethodCallExpression methodCallExpr
+                && methodCallExpr.Method.Name == "op_Implicit"
+                && methodCallExpr.Method.DeclaringType != null
+                && methodCallExpr.Method.DeclaringType.IsGenericType
+                && methodCallExpr.Arguments.Count == 1)
+            {
+                var genericTypeDefinition = methodCallExpr.Method.DeclaringType.GetGenericTypeDefinition();
+                if (genericTypeDefinition == typeof(Span<>) || genericTypeDefinition == typeof(ReadOnlySpan<>))
+                {
+                    result = methodCallExpr.Arguments[0];
+                    return true;
+                }
+            }
+
+            result = null;
+            return false;
+        }
+#endif
+
         // <summary>
         // Handles MethodCall patterns:
         // - Operator overloads
@@ -132,6 +173,45 @@ private static bool IsConstantZero(Expression expression)
         [SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
         internal override Expression VisitMethodCall(MethodCallExpression m)
         {
+#if NETSTANDARD2_1
+            // .NET 10 made changes to overload resolution to prefer Span-based overloads when those exist ("first-class spans").
+            // Unfortunately, EF6's query translator does not recognize MemoryExtensions methods, so we rewrite e.g.
+            // MemoryExtensions.Contains to Enumerable.Contains here.
+            // See:
+            //   https://github.com/dotnet/ef6/issues/2322
+            //   https://github.com/dotnet/runtime/issues/109757
+            //   https://github.com/dotnet/efcore/pull/35339
+            // Note: This check must occur before base.VisitMethodCall() to detect op_Implicit before it's normalized to Convert.
+            if (m.Method.DeclaringType == typeof(MemoryExtensions))
+            {
+                switch (m.Method.Name)
+                {
+                    // Note that MemoryExtensions.Contains has an optional 3rd ComparisonType parameter; we only match when
+                    // it's null.
+                    case nameof(MemoryExtensions.Contains)
+                        when m.Arguments.Count >= 2
+                        && (m.Arguments.Count == 2
+                            || m.Arguments.Count == 3 && m.Arguments[2] is ConstantExpression constantExpr && constantExpr.Value == null)
+                        && TryUnwrapSpanImplicitCast(m.Arguments[0], out var unwrappedSpanArg):
+                    {
+                        var containsMethod = _enumerableContainsMethod.Value.MakeGenericMethod(m.Method.GetGenericArguments()[0]);
+
+                        return Visit(Expression.Call(containsMethod, unwrappedSpanArg, m.Arguments[1]));
+                    }
+
+                    case nameof(MemoryExtensions.SequenceEqual)
+                        when m.Arguments.Count == 2
+                        && TryUnwrapSpanImplicitCast(m.Arguments[0], out var unwrappedSpanArg1)
+                        && TryUnwrapSpanImplicitCast(m.Arguments[1], out var unwrappedSpanArg2):
+                    {
+                        var sequenceEqualMethod = _enumerableSequenceEqualMethod.Value.MakeGenericMethod(m.Method.GetGenericArguments()[0]);
+
+                        return Visit(Expression.Call(sequenceEqualMethod, unwrappedSpanArg1, unwrappedSpanArg2));
+                    }
+                }
+            }
+#endif
+
             m = (MethodCallExpression)base.VisitMethodCall(m);
 
             if (m.Method.IsStatic)
diff --git a/test/FunctionalTests/Query/LinqToEntities/ContainsTests.cs b/test/FunctionalTests/Query/LinqToEntities/ContainsTests.cs
index fe948ea948..d59d078095 100644
--- a/test/FunctionalTests/Query/LinqToEntities/ContainsTests.cs
+++ b/test/FunctionalTests/Query/LinqToEntities/ContainsTests.cs
@@ -288,8 +288,8 @@ public void Contains_throws_for_constant_null_list()
         public void Contains_on_non_static_collection_of_enums()
         {
             const string expectedSql =
-                @"SELECT 
-CASE WHEN ( EXISTS (SELECT 
+                @"SELECT
+CASE WHEN ( EXISTS (SELECT
 	1 AS [C1]
 	FROM [dbo].[Books] AS [Extent2]
 	WHERE 0 = [Extent2].[Genre]
@@ -305,5 +305,32 @@ FROM [dbo].[Books] AS [Extent2]
                 QueryTestHelpers.VerifyDbQuery(query, expectedSql);
             }
         }
+
+        [Fact]
+        public void EnumerableContains_with_string_array_on_net10_is_translated_to_expected_sql()
+        {
+            // On .NET 10+, the C# compiler prefers Span-based overloads ("first-class spans").
+            // This means array.Contains(value) compiles to MemoryExtensions.Contains(array.AsSpan(), value)
+            // instead of Enumerable.Contains(array, value). EF6 needs to rewrite these back to
+            // Enumerable.Contains for the LINQ interpreter to work.
+            const string expectedSql =
+                @"SELECT
+[Extent1].[Id] AS [Id]
+FROM [dbo].[Books] AS [Extent1]
+WHERE [Extent1].[Title] IN (N'Title1', N'Title2')";
+
+            var array = new[] { "Title1", "Title2" };
+
+            using (var context = new UnicodeContext())
+            {
+                context.Configuration.UseDatabaseNullSemantics = true;
+
+                var query = from book in context.Books
+                            where array.Contains(book.Title)
+                            select book.Id;
+
+                QueryTestHelpers.VerifyDbQuery(query, expectedSql);
+            }
+        }
     }
 }
diff --git a/test/UnitTests/Core/Objects/ELinq/LinqExpressionNormalizerTests.cs b/test/UnitTests/Core/Objects/ELinq/LinqExpressionNormalizerTests.cs
index a93553bb31..26436665c7 100644
--- a/test/UnitTests/Core/Objects/ELinq/LinqExpressionNormalizerTests.cs
+++ b/test/UnitTests/Core/Objects/ELinq/LinqExpressionNormalizerTests.cs
@@ -1,8 +1,13 @@
-// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
 
 namespace System.Data.Entity.Core.Objects.ELinq
 {
     using Xunit;
+#if NET5_0_OR_GREATER
+    using System.Linq;
+    using System.Linq.Expressions;
+    using System.Reflection;
+#endif
 
     public class LinqExpressionNormalizerTests
     {
@@ -11,5 +16,177 @@ public void MethodInfo_fields_are_initialized()
         {
             Assert.NotNull(LinqExpressionNormalizer.RelationalOperatorPlaceholderMethod);
         }
+
+#if NET5_0_OR_GREATER
+
+        [Fact]
+        public void MemoryExtensions_Contains_with_ReadOnlySpan_is_rewritten_to_Enumerable_Contains()
+        {
+            // Test: MemoryExtensions.Contains<T>(ReadOnlySpan<T>, T)
+            var array = new[] { "Title1", "Title2", "Title3" };
+            var testValue = "Title1";
+
+            var arrayExpr = Expression.Constant(array);
+            var testValueExpr = Expression.Constant(testValue);
+
+            // Get ReadOnlySpan<T>.op_Implicit method
+            var spanType = typeof(ReadOnlySpan<>).MakeGenericType(typeof(string));
+            var implicitMethod = spanType.GetMethod("op_Implicit", new[] { typeof(string[]) });
+            var spanExpr = Expression.Call(implicitMethod, arrayExpr);
+
+            // Get MemoryExtensions.Contains<T>(ReadOnlySpan<T>, T)
+            // Note: There are both Span<T> and ReadOnlySpan<T> versions, we want ReadOnlySpan
+            var memExtContainsGeneric = typeof(MemoryExtensions).GetMethods(BindingFlags.Public | BindingFlags.Static)
+                .Where(m => m.Name == nameof(MemoryExtensions.Contains)
+                    && m.IsGenericMethodDefinition
+                    && m.GetParameters().Length == 2
+                    && m.GetParameters()[0].ParameterType.GetGenericTypeDefinition() == typeof(ReadOnlySpan<>))
+                .Single();
+            var memExtContains = memExtContainsGeneric.MakeGenericMethod(typeof(string));
+
+            var methodCall = Expression.Call(memExtContains, spanExpr, testValueExpr);
+
+            // Normalize the expression
+            var normalizer = new LinqExpressionNormalizer();
+            var normalized = normalizer.Visit(methodCall);
+
+            // Verify it was rewritten to Enumerable.Contains
+            var normalizedCall = Assert.IsAssignableFrom<MethodCallExpression>(normalized);
+            Assert.Equal(nameof(Enumerable.Contains), normalizedCall.Method.Name);
+            Assert.Equal(typeof(Enumerable), normalizedCall.Method.DeclaringType);
+            Assert.Equal(2, normalizedCall.Arguments.Count);
+
+            // The first argument should be the unwrapped array
+            Assert.IsAssignableFrom<ConstantExpression>(normalizedCall.Arguments[0]);
+            var unwrappedArray = ((ConstantExpression)normalizedCall.Arguments[0]).Value;
+            Assert.Same(array, unwrappedArray);
+        }
+
+        [Fact]
+        public void MemoryExtensions_Contains_with_Span_is_rewritten_to_Enumerable_Contains()
+        {
+            // Test: MemoryExtensions.Contains<T>(Span<T>, T)
+            var array = new[] { "Title1", "Title2", "Title3" };
+            var testValue = "Title1";
+
+            var arrayExpr = Expression.Constant(array);
+            var testValueExpr = Expression.Constant(testValue);
+
+            // Get Span<T>.op_Implicit method
+            var spanType = typeof(Span<>).MakeGenericType(typeof(string));
+            var implicitMethod = spanType.GetMethod("op_Implicit", new[] { typeof(string[]) });
+            var spanExpr = Expression.Call(implicitMethod, arrayExpr);
+
+            // Get MemoryExtensions.Contains<T>(Span<T>, T)
+            var memExtContainsGeneric = typeof(MemoryExtensions).GetMethods(BindingFlags.Public | BindingFlags.Static)
+                .Where(m => m.Name == nameof(MemoryExtensions.Contains)
+                    && m.IsGenericMethodDefinition
+                    && m.GetParameters().Length == 2
+                    && m.GetParameters()[0].ParameterType.GetGenericTypeDefinition() == typeof(Span<>))
+                .Single();
+            var memExtContains = memExtContainsGeneric.MakeGenericMethod(typeof(string));
+
+            var methodCall = Expression.Call(memExtContains, spanExpr, testValueExpr);
+
+            // Normalize the expression
+            var normalizer = new LinqExpressionNormalizer();
+            var normalized = normalizer.Visit(methodCall);
+
+            // Verify it was rewritten to Enumerable.Contains
+            var normalizedCall = Assert.IsAssignableFrom<MethodCallExpression>(normalized);
+            Assert.Equal(nameof(Enumerable.Contains), normalizedCall.Method.Name);
+            Assert.Equal(typeof(Enumerable), normalizedCall.Method.DeclaringType);
+            Assert.Equal(2, normalizedCall.Arguments.Count);
+
+            // The first argument should be the unwrapped array
+            Assert.IsAssignableFrom<ConstantExpression>(normalizedCall.Arguments[0]);
+            var unwrappedArray = ((ConstantExpression)normalizedCall.Arguments[0]).Value;
+            Assert.Same(array, unwrappedArray);
+        }
+
+#if NET10_0_OR_GREATER
+        [Fact]
+        public void MemoryExtensions_Contains_with_null_comparer_is_rewritten()
+        {
+            // Test: MemoryExtensions.Contains<T>(ReadOnlySpan<T>, T, IEqualityComparer<T>) with null comparer
+            // Note: This 3-parameter overload was added in .NET 10
+            // The fix rewrites this when the comparer parameter is null
+            var array = new[] { "Title1", "Title2", "Title3" };
+            var testValue = "Title1";
+
+            var arrayExpr = Expression.Constant(array);
+            var testValueExpr = Expression.Constant(testValue);
+            var nullComparerExpr = Expression.Constant(null, typeof(System.Collections.Generic.IEqualityComparer<string>));
+
+            // Get ReadOnlySpan<T>.op_Implicit method
+            var spanType = typeof(ReadOnlySpan<>).MakeGenericType(typeof(string));
+            var implicitMethod = spanType.GetMethod("op_Implicit", new[] { typeof(string[]) });
+            var spanExpr = Expression.Call(implicitMethod, arrayExpr);
+
+            // Get MemoryExtensions.Contains<T>(ReadOnlySpan<T>, T, IEqualityComparer<T>)
+            var memExtContainsGeneric = typeof(MemoryExtensions).GetMethods(BindingFlags.Public | BindingFlags.Static)
+                .Where(m => m.Name == nameof(MemoryExtensions.Contains)
+                    && m.IsGenericMethodDefinition
+                    && m.GetParameters().Length == 3
+                    && m.GetParameters()[0].ParameterType.GetGenericTypeDefinition() == typeof(ReadOnlySpan<>)
+                    && m.GetParameters()[2].ParameterType.GetGenericTypeDefinition() == typeof(System.Collections.Generic.IEqualityComparer<>))
+                .Single();
+            var memExtContains = memExtContainsGeneric.MakeGenericMethod(typeof(string));
+
+            var methodCall = Expression.Call(memExtContains, spanExpr, testValueExpr, nullComparerExpr);
+
+            // Normalize the expression
+            var normalizer = new LinqExpressionNormalizer();
+            var normalized = normalizer.Visit(methodCall);
+
+            // Verify it was rewritten to Enumerable.Contains
+            var normalizedCall = Assert.IsAssignableFrom<MethodCallExpression>(normalized);
+            Assert.Equal(nameof(Enumerable.Contains), normalizedCall.Method.Name);
+            Assert.Equal(typeof(Enumerable), normalizedCall.Method.DeclaringType);
+            Assert.Equal(2, normalizedCall.Arguments.Count);
+        }
+#endif
+
+        [Fact]
+        public void MemoryExtensions_SequenceEqual_is_rewritten_to_Enumerable_SequenceEqual()
+        {
+            // Test that SequenceEqual is also rewritten correctly
+
+            var array1 = new[] { 1, 2, 3 };
+            var array2 = new[] { 1, 2, 3 };
+
+            var array1Expr = Expression.Constant(array1);
+            var array2Expr = Expression.Constant(array2);
+
+            // Get the Span<T> op_Implicit method
+            var spanType = typeof(ReadOnlySpan<>).MakeGenericType(typeof(int));
+            var implicitMethod = spanType.GetMethod("op_Implicit", new[] { typeof(int[]) });
+            var span1Expr = Expression.Call(implicitMethod, array1Expr);
+            var span2Expr = Expression.Call(implicitMethod, array2Expr);
+
+            // Get MemoryExtensions.SequenceEqual<T>(ReadOnlySpan<T>, ReadOnlySpan<T>) - the generic method with 2 parameters
+            // Note: There are both Span<T> and ReadOnlySpan<T> versions, we want ReadOnlySpan
+            var memExtSequenceEqualGeneric = typeof(MemoryExtensions).GetMethods(BindingFlags.Public | BindingFlags.Static)
+                .Where(m => m.Name == nameof(MemoryExtensions.SequenceEqual)
+                    && m.IsGenericMethodDefinition
+                    && m.GetParameters().Length == 2
+                    && m.GetParameters()[0].ParameterType.GetGenericTypeDefinition() == typeof(ReadOnlySpan<>))
+                .Single();
+            var memExtSequenceEqual = memExtSequenceEqualGeneric.MakeGenericMethod(typeof(int));
+
+            var methodCall = Expression.Call(memExtSequenceEqual, span1Expr, span2Expr);
+
+            // Normalize the expression
+            var normalizer = new LinqExpressionNormalizer();
+            var normalized = normalizer.Visit(methodCall);
+
+            // Verify it was rewritten to Enumerable.SequenceEqual
+            var normalizedCall = Assert.IsAssignableFrom<MethodCallExpression>(normalized);
+            Assert.Equal(nameof(Enumerable.SequenceEqual), normalizedCall.Method.Name);
+            Assert.Equal(typeof(Enumerable), normalizedCall.Method.DeclaringType);
+            Assert.Equal(2, normalizedCall.Arguments.Count);
+        }
+
+#endif
     }
 }
diff --git a/test/UnitTests/UnitTests.csproj b/test/UnitTests/UnitTests.csproj
index 0ae59776ae..7cfba91091 100644
--- a/test/UnitTests/UnitTests.csproj
+++ b/test/UnitTests/UnitTests.csproj
@@ -1,12 +1,12 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <RootNamespace>System.Data.Entity</RootNamespace>
     <AssemblyName>EntityFramework.UnitTests</AssemblyName>
-    <TargetFramework>$(NetFrameworkToolCurrent)</TargetFramework>
+    <TargetFrameworks>$(NetFrameworkToolCurrent);$(DefaultNetCoreTargetFramework)</TargetFrameworks>
   </PropertyGroup>
 
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
     <Reference Include="Microsoft.VisualBasic" />
     <Reference Include="Microsoft.CSharp" />
     <Reference Include="System.ComponentModel.DataAnnotations" />
@@ -16,6 +16,17 @@
     <Reference Include="System.Windows.Forms" />
   </ItemGroup>
 
+  <!--
+    For .NET 10+ builds, only include Span-related tests. The vast majority of the UnitTests project
+    depends on .NET Framework-specific infrastructure (SqlServerCe, Remoting, BinaryFormatter, etc.)
+    and was not designed for cross-platform use. Rather than exclude hundreds of tests, we include
+    only the tests relevant for .NET 10+ scenarios.
+  -->
+  <ItemGroup Condition="'$(TargetFramework)' == '$(DefaultNetCoreTargetFramework)'">
+    <Compile Remove="**\*.cs" />
+    <Compile Include="**\LinqExpressionNormalizerTests.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <None Remove="TestDataFiles\SqlOperation_Basic.sql" />
   </ItemGroup>