diff --git a/ChangeLog/7.1.2_dev.txt b/ChangeLog/7.1.2_dev.txt
index e69de29bb2..78b15d4fc6 100644
--- a/ChangeLog/7.1.2_dev.txt
+++ b/ChangeLog/7.1.2_dev.txt
@@ -0,0 +1 @@
+[main] Addressed issue when cycles in Entity dependency graph were not detected
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm/Sorting/TopologicalSorter.cs b/Orm/Xtensive.Orm/Sorting/TopologicalSorter.cs
index 0a30a6b5e0..282ee03543 100644
--- a/Orm/Xtensive.Orm/Sorting/TopologicalSorter.cs
+++ b/Orm/Xtensive.Orm/Sorting/TopologicalSorter.cs
@@ -9,7 +9,9 @@
 using Xtensive.Collections;
 using System.Linq;
 using Xtensive.Core;
-
+using DotNetNotNullAttribute = System.Diagnostics.CodeAnalysis.NotNullAttribute;
+using JBNotNullAttribute = JetBrains.Annotations.NotNullAttribute;
+using JBCanBeNullAttribute = JetBrains.Annotations.CanBeNullAttribute;
 
 namespace Xtensive.Sorting
 {
@@ -29,6 +31,7 @@ public static class TopologicalSorter
     /// Sorting result, if there were no loops;
     /// otherwise, <see langword="null"/>.
     /// </returns>
+    [JBCanBeNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem>(IEnumerable<TNodeItem> items, Predicate<TNodeItem, TNodeItem> connector) =>
       Sort(items, connector, out List<Node<TNodeItem, object>> loops);
 
@@ -43,6 +46,7 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem>(IEnumerable<TNodeItem> item
     /// Sorting result, if there were no loops;
     /// otherwise, <see langword="null"/>.
     /// </returns>
+    [JBCanBeNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(IEnumerable<TNodeItem> items, Predicate<TNodeItem, TNodeItem> connector) =>
       SortToList(items, connector, out List<Node<TNodeItem, object>> loops);
 
@@ -59,6 +63,7 @@ public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(IEnumerable<TNodeIt
     /// otherwise, <see langword="null"/>.
     /// In this case <paramref name="loops"/> will contain only the loop edges.
     /// </returns>
+    [JBCanBeNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem>(
       IEnumerable<TNodeItem> items,
       Predicate<TNodeItem, TNodeItem> connector,
@@ -83,6 +88,7 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem>(
     /// otherwise, <see langword="null"/>.
     /// In this case <paramref name="loops"/> will contain only the loop edges.
     /// </returns>
+    [JBCanBeNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(
       IEnumerable<TNodeItem> items,
       Predicate<TNodeItem, TNodeItem> connector,
@@ -105,6 +111,8 @@ public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(
     /// <returns>
     /// Sorting result
     /// </returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem>(
       IEnumerable<TNodeItem> items,
       Predicate<TNodeItem, TNodeItem> connector,
@@ -121,6 +129,8 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem>(
     /// <returns>
     /// Sorting result
     /// </returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(
       IEnumerable<TNodeItem> items,
       Predicate<TNodeItem, TNodeItem> connector,
@@ -138,6 +148,8 @@ public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(
     /// <returns>
     /// Sorting result
     /// </returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem>(
       IEnumerable<TNodeItem> items,
       Predicate<TNodeItem, TNodeItem> connector,
@@ -161,6 +173,8 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem>(
     /// <returns>
     /// Sorting result
     /// </returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(
       IEnumerable<TNodeItem> items,
       Predicate<TNodeItem, TNodeItem> connector,
@@ -181,9 +195,16 @@ public static IReadOnlyList<TNodeItem> SortToList<TNodeItem>(
     /// <returns>Sorting result, if there were no loops;
     /// otherwise, <see langword="null" />. 
     /// In this case <paramref name="nodes"/> will contain only the loop edges.</returns>
+    [JBCanBeNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem, TConnectionItem>(
       List<Node<TNodeItem, TConnectionItem>> nodes,
-      out List<Node<TNodeItem, TConnectionItem>> loops) => SortInternal(nodes, out loops).sorted ?? Array.Empty<TNodeItem>();
+      out List<Node<TNodeItem, TConnectionItem>> loops)
+    {
+      var (sorted, count) = SortInternal(nodes, out loops) /* ?? Array.Empty<TNodeItem>()*/;
+      return (sorted is not null && count == 0)
+        ? Array.Empty<TNodeItem>()
+        : sorted;
+    }
 
     /// <summary>
     /// Sorts the specified oriented graph of the nodes in their topological order
@@ -194,14 +215,17 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem, TConnectionItem>(
     /// <returns>Sorting result, if there were no loops;
     /// otherwise, <see langword="null" />. 
     /// In this case <paramref name="nodes"/> will contain only the loop edges.</returns>
+    [JBCanBeNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem, TConnectionItem>(
       List<Node<TNodeItem, TConnectionItem>> nodes,
       out List<Node<TNodeItem, TConnectionItem>> loops)
     {
       var (sorted, count) = SortInternal(nodes, out loops);
-      return (sorted is null || count == 0)
-        ? Array.Empty<TNodeItem>()
-        : sorted.ToArray(count);
+      return (sorted is null)
+        ? null
+        : count == 0
+          ? Array.Empty<TNodeItem>()
+          : sorted.ToArray(count);
     }
 
     /// <summary>
@@ -211,6 +235,8 @@ public static IReadOnlyList<TNodeItem> SortToList<TNodeItem, TConnectionItem>(
     /// <param name="nodes">The nodes.</param>
     /// <param name="removedEdges">Edges removed to make graph non-cyclic.</param>
     /// <returns>Sorting result.</returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem, TConnectionItem>(
       IEnumerable<Node<TNodeItem, TConnectionItem>> nodes,
       out List<NodeConnection<TNodeItem, TConnectionItem>> removedEdges) =>
@@ -223,6 +249,8 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem, TConnectionItem>(
     /// <param name="nodes">The nodes.</param>
     /// <param name="removedEdges">Edges removed to make graph non-cyclic.</param>
     /// <returns>Sorting result.</returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem, TConnectionItem>(
       IEnumerable<Node<TNodeItem, TConnectionItem>> nodes,
       out List<NodeConnection<TNodeItem, TConnectionItem>> removedEdges) =>
@@ -236,6 +264,8 @@ public static IReadOnlyList<TNodeItem> SortToList<TNodeItem, TConnectionItem>(
     /// <param name="removedEdges">Edges removed to make graph non-cyclic.</param>
     /// <param name="removeWholeNode">If <see langword="true"/> removes whole node in the case of loop, otherwise removes only one edge.</param>
     /// <returns>Sorting result.</returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IEnumerable<TNodeItem> Sort<TNodeItem, TConnectionItem>(
         IEnumerable<Node<TNodeItem, TConnectionItem>> nodes,
         out List<NodeConnection<TNodeItem, TConnectionItem>> removedEdges,
@@ -250,6 +280,8 @@ public static IEnumerable<TNodeItem> Sort<TNodeItem, TConnectionItem>(
     /// <param name="removedEdges">Edges removed to make graph non-cyclic.</param>
     /// <param name="removeWholeNode">If <see langword="true"/> removes whole node in the case of loop, otherwise removes only one edge.</param>
     /// <returns>Sorting result.</returns>
+    [return: DotNetNotNull]
+    [JBNotNull]
     public static IReadOnlyList<TNodeItem> SortToList<TNodeItem, TConnectionItem>(
       IEnumerable<Node<TNodeItem, TConnectionItem>> nodes,
       out List<NodeConnection<TNodeItem, TConnectionItem>> removedEdges,