diff --git a/Orm/Xtensive.Orm.Tests/Indexing/ForeignKeyInfoTest.cs b/Orm/Xtensive.Orm.Tests/Indexing/ForeignKeyInfoTest.cs
index 89b023b30e..7e48cd77c6 100644
--- a/Orm/Xtensive.Orm.Tests/Indexing/ForeignKeyInfoTest.cs
+++ b/Orm/Xtensive.Orm.Tests/Indexing/ForeignKeyInfoTest.cs
@@ -4,6 +4,7 @@
 // Created by: Ivan Galkin
 // Created:    2009.03.23
 
+using System;
 using Xtensive.Core;
 using Xtensive.Orm;
 using Xtensive.Orm.Upgrade.Model;
diff --git a/Orm/Xtensive.Orm.Tests/Indexing/PrimaryIndexInfoTest.cs b/Orm/Xtensive.Orm.Tests/Indexing/PrimaryIndexInfoTest.cs
index 7e1901b962..cd82df5ef0 100644
--- a/Orm/Xtensive.Orm.Tests/Indexing/PrimaryIndexInfoTest.cs
+++ b/Orm/Xtensive.Orm.Tests/Indexing/PrimaryIndexInfoTest.cs
@@ -11,7 +11,6 @@
 using Xtensive.Core;
 using Xtensive.Orm.Tests;
 using Xtensive.Orm.Upgrade.Model;
-using AggregateException = Xtensive.Core.AggregateException;
 
 namespace Xtensive.Orm.Tests.Indexing
 {
diff --git a/Orm/Xtensive.Orm.Tests/Indexing/SecondaryIndexInfoTest.cs b/Orm/Xtensive.Orm.Tests/Indexing/SecondaryIndexInfoTest.cs
index adf2089c20..30028754f4 100644
--- a/Orm/Xtensive.Orm.Tests/Indexing/SecondaryIndexInfoTest.cs
+++ b/Orm/Xtensive.Orm.Tests/Indexing/SecondaryIndexInfoTest.cs
@@ -10,7 +10,6 @@
 using Xtensive.Core;
 using Xtensive.Orm.Tests;
 using Xtensive.Orm.Upgrade.Model;
-using AggregateException = Xtensive.Core.AggregateException;
 
 namespace Xtensive.Orm.Tests.Indexing
 {
diff --git a/Orm/Xtensive.Orm.Tests/Indexing/StorageInfoTest.cs b/Orm/Xtensive.Orm.Tests/Indexing/StorageInfoTest.cs
index 40c59b0805..4fb69efd34 100644
--- a/Orm/Xtensive.Orm.Tests/Indexing/StorageInfoTest.cs
+++ b/Orm/Xtensive.Orm.Tests/Indexing/StorageInfoTest.cs
@@ -10,7 +10,6 @@
 using Xtensive.Orm.Tests;
 using Xtensive.Modelling.Actions;
 using Xtensive.Orm.Upgrade.Model;
-using AggregateException = Xtensive.Core.AggregateException;
 
 namespace Xtensive.Orm.Tests.Indexing
 {
diff --git a/Orm/Xtensive.Orm/Core/Exceptions/AggregateException.cs b/Orm/Xtensive.Orm/Core/Exceptions/AggregateException.cs
deleted file mode 100644
index 928e627457..0000000000
--- a/Orm/Xtensive.Orm/Core/Exceptions/AggregateException.cs
+++ /dev/null
@@ -1,165 +0,0 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
-// Created by: Alex Yakunin
-// Created:    2008.07.03
-
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.Runtime.Serialization;
-using System.Security;
-using System.Text;
-using System.Linq;
-
-namespace Xtensive.Core
-{
-  /// <summary>
-  /// Aggregates a set of caught exceptions.
-  /// </summary>
-  [Serializable]
-  public class AggregateException : Exception
-  {
-    private Exception[] exceptions;
-
-    /// <summary>
-    /// Gets the list of caught exceptions.
-    /// </summary>
-    public IReadOnlyList<Exception> Exceptions
-    {
-      [DebuggerStepThrough]
-      get { return exceptions; }
-    }
-
-    /// <summary>
-    /// Gets the "flat" list with all aggregated exceptions. 
-    /// If other <see cref=" AggregateException"/>s were aggregated, 
-    /// their inner exceptions are included instead of them.
-    /// </summary>
-    /// <returns>Flat list of aggregated exceptions.</returns>
-    public List<Exception> GetFlatExceptions()
-    {
-      var result = new List<Exception>();
-
-      foreach (var exception in exceptions) {
-        var ae = exception as AggregateException;
-        if (ae!=null)
-          result.AddRange(ae.GetFlatExceptions());
-        else
-          result.Add(exception);
-      }
-
-      return result;
-    }
-
-    /// <inheritdoc/>
-    public override string ToString()
-    {
-      StringBuilder sb = new StringBuilder(64);
-      sb.Append(base.ToString());
-      sb.AppendFormat("\r\n{0}:", Strings.OriginalExceptions);
-      int i = 1;
-      foreach (Exception exception in exceptions)
-        sb.AppendFormat("\r\n{0}: {1}", i++, exception);
-      return sb.ToString();
-    }
-
-    #region Private \ internal methods
-
-    private void SetExceptions(Exception[] exceptions)
-    {
-      this.exceptions = exceptions;
-    }
-
-    private void SetExceptions(Exception exception)
-    {
-      exceptions =  new Exception[] { exception };
-    }
-
-    #endregion
-
-
-    // Constructors
-    
-    /// <summary>
-    /// Initializes a new instance of this type.
-    /// </summary>
-    public AggregateException()
-      : base(Strings.ExASetOfExceptionsIsCaught)
-    {
-    }
-
-    /// <summary>
-    /// Initializes a new instance of this type.
-    /// </summary>
-    /// <param name="text">Text of message.</param>
-    public AggregateException(string text)
-      : base(text)
-    {
-    }
-
-    /// <summary>
-    /// Initializes a new instance of this type.
-    /// </summary>
-    /// <param name="message">Text of message.</param>
-    /// <param name="innerException">Inner exception.</param>
-    public AggregateException(string message, Exception innerException) 
-      : base(message, innerException)
-    {
-      SetExceptions(innerException);
-    }
-
-    /// <summary>
-    /// Initializes a new instance of this type.
-    /// </summary>
-    /// <param name="exceptions">Inner exceptions.</param>
-    public AggregateException(Exception[] exceptions) 
-      : base(Strings.ExASetOfExceptionsIsCaught, exceptions.First())
-    {
-      SetExceptions(exceptions);
-    }
-
-    /// <summary>
-    /// Initializes a new instance of this type.
-    /// </summary>
-    /// <param name="message">Text of message.</param>
-    /// <param name="exceptions">Inner exceptions.</param>
-    public AggregateException(string message, Exception[] exceptions) 
-      : base(message, exceptions.First())
-    {
-      SetExceptions(exceptions);
-    }
-
-
-    // Serialization
-
-    /// <summary>
-    /// Deserializes instance of this type.
-    /// </summary>
-    /// <param name="info"></param>
-    /// <param name="context"></param>
-#if NET8_0_OR_GREATER
-    [Obsolete(DiagnosticId = "SYSLIB0051")]
-#endif
-    protected AggregateException(SerializationInfo info, StreamingContext context)
-      : base(info, context)
-    {
-      exceptions = (Exception[]) info.GetValue("Exceptions", typeof (Exception[]));
-    }
-
-    /// <summary>
-    /// Serializes instance of this type.
-    /// </summary>
-    /// <param name="info"></param>
-    /// <param name="context"></param>
-    [SecurityCritical]
-#if NET8_0_OR_GREATER
-    [Obsolete(DiagnosticId = "SYSLIB0051")]
-#endif
-    public override void GetObjectData(SerializationInfo info, StreamingContext context)
-    {
-      base.GetObjectData(info, context);
-      info.AddValue("Exceptions", exceptions);
-    }
-  }
-}
\ No newline at end of file