Fix in-memory corruption of nested owned entities after SaveChanges when navigation is replaced

src/EFCore/ChangeTracking/Internal/EntityGraphAttacher.cs

@@ -102,7 +102,11 @@ private bool PaintAction(
         SetReferenceLoaded(node);
 
         var internalEntityEntry = node.GetInfrastructure();
-        if (internalEntityEntry.EntityState != EntityState.Detached
+        var sourceEntry = node.SourceEntry?.GetInfrastructure();
+
+        if ((internalEntityEntry.EntityState != EntityState.Detached
+                && (internalEntityEntry.EntityState != EntityState.Deleted
+                    || sourceEntry?.SharedIdentityEntry == null))
             || (_visited != null && _visited.Contains(internalEntityEntry.Entity)))
         {
             return false;
@@ -114,7 +118,7 @@ private bool PaintAction(
 
         if (internalEntityEntry.StateManager.ResolveToExistingEntry(
                 internalEntityEntry,
-                node.InboundNavigation, node.SourceEntry?.GetInfrastructure()))
+                node.InboundNavigation, sourceEntry))
         {
             (_visited ??= new HashSet<object>(ReferenceEqualityComparer.Instance)).Add(internalEntityEntry.Entity);
         }
@@ -139,7 +143,10 @@ private async Task<bool> PaintActionAsync(
         SetReferenceLoaded(node);
 
         var internalEntityEntry = node.GetInfrastructure();
-        if (internalEntityEntry.EntityState != EntityState.Detached
+        var sourceEntry = node.SourceEntry?.GetInfrastructure();
+        if ((internalEntityEntry.EntityState != EntityState.Detached
+                && (internalEntityEntry.EntityState != EntityState.Deleted
+                    || sourceEntry?.SharedIdentityEntry == null))
             || (_visited != null && _visited.Contains(internalEntityEntry.Entity)))
         {
             return false;
@@ -151,7 +158,7 @@ private async Task<bool> PaintActionAsync(
 
         if (internalEntityEntry.StateManager.ResolveToExistingEntry(
                 internalEntityEntry,
-                node.InboundNavigation, node.SourceEntry?.GetInfrastructure()))
+                node.InboundNavigation, sourceEntry))
         {
             (_visited ??= []).Add(internalEntityEntry.Entity);
         }

src/EFCore/ChangeTracking/Internal/StateManager.cs

@@ -1208,6 +1208,14 @@ public virtual void CascadeChanges(bool force)
     /// </summary>
     public virtual void CascadeDelete(InternalEntityEntry entry, bool force, IEnumerable<IForeignKey>? foreignKeys = null)
     {
+        // When an owned entity is replaced (e.g., via record 'with' expression), the old entry is
+        // marked Deleted and a new entry with the same key is linked via SharedIdentityEntry.
+        // Skip cascade from the old entry since the replacement handles its own dependents.
+        if (entry.SharedIdentityEntry != null)
+        {
+            return;
+        }
+
         var doCascadeDelete = force || CascadeDeleteTiming != CascadeTiming.Never;
         var principalIsDetached = entry.EntityState == EntityState.Detached;
 

test/EFCore.Relational.Specification.Tests/Update/JsonUpdateTestBase.cs

@@ -3671,6 +3671,67 @@ public virtual Task Edit_single_property_with_non_ascii_characters()
                Assert.Equal("测试1", result.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf.SomethingSomething);
            });
 
+    [ConditionalFact]
+    public virtual Task Replace_json_reference_root_preserves_nested_owned_entities_in_memory()
+        => TestHelpers.ExecuteWithStrategyInTransactionAsync(
+            CreateContext,
+            UseTransaction,
+            async context =>
+            {
+                var query = await context.JsonEntitiesBasic.ToListAsync();
+                var entity = query.Single();
+
+                // Save original leaf value
+                var originalLeaf = entity.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf;
+                var originalLeafValue = originalLeaf.SomethingSomething;
+
+                // Replace the owned reference with a new instance that shares nested reference navigations
+                var oldRoot = entity.OwnedReferenceRoot;
+                entity.OwnedReferenceRoot = new JsonOwnedRoot
+                {
+                    Name = "Modified",
+                    Number = oldRoot.Number,
+                    Names = oldRoot.Names,
+                    Numbers = oldRoot.Numbers,
+                    OwnedReferenceBranch = new JsonOwnedBranch
+                    {
+                        Id = oldRoot.OwnedReferenceBranch.Id,
+                        Date = oldRoot.OwnedReferenceBranch.Date,
+                        Enum = oldRoot.OwnedReferenceBranch.Enum,
+                        Fraction = oldRoot.OwnedReferenceBranch.Fraction,
+                        NullableEnum = oldRoot.OwnedReferenceBranch.NullableEnum,
+                        Enums = oldRoot.OwnedReferenceBranch.Enums,
+                        NullableEnums = oldRoot.OwnedReferenceBranch.NullableEnums,
+                        OwnedReferenceLeaf = originalLeaf,
+                        OwnedCollectionLeaf = [],
+                    },
+                    OwnedCollectionBranch = [],
+                };
+
+                // Before DetectChanges, leaf should be accessible
+                Assert.Same(originalLeaf, entity.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf);
+
+                context.ChangeTracker.DetectChanges();
+
+                // After DetectChanges, leaf should still be accessible
+                Assert.NotNull(entity.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf);
+
+                ClearLog();
+                await context.SaveChangesAsync();
+
+                // After SaveChanges, nested owned entities should still be accessible in memory
+                Assert.NotNull(entity.OwnedReferenceRoot.OwnedReferenceBranch);
+                Assert.NotNull(entity.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf);
+                Assert.Equal(originalLeafValue, entity.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf.SomethingSomething);
+            },
+            async context =>
+            {
+                var result = await context.Set<JsonEntityBasic>().SingleAsync();
+                Assert.Equal("Modified", result.OwnedReferenceRoot.Name);
+                Assert.NotNull(result.OwnedReferenceRoot.OwnedReferenceBranch);
+                Assert.NotNull(result.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf);
+            });
+
     public void UseTransaction(DatabaseFacade facade, IDbContextTransaction transaction)
         => facade.UseTransaction(transaction.GetDbTransaction());