Index: java/org/apache/catalina/ha/session/DeltaSession.java
===================================================================
--- java/org/apache/catalina/ha/session/DeltaSession.java	(revision 1703678)
+++ java/org/apache/catalina/ha/session/DeltaSession.java	(working copy)
@@ -24,6 +24,7 @@
 import java.io.ObjectOutput;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.io.WriteAbortedException;
 import java.security.Principal;
 import java.util.ArrayList;
 import java.util.Hashtable;
@@ -771,9 +772,16 @@
         isValid = true;
         for (int i = 0; i < n; i++) {
             String name = (String) stream.readObject();
-            Object value = stream.readObject();
-            if ( (value instanceof String) && (value.equals(NOT_SERIALIZED)))
-                continue;
+            final Object value;
+            try {
+                value = stream.readObject();
+            } catch (WriteAbortedException wae) {
+                if (wae.getCause() instanceof NotSerializableException) {
+                    // Skip non serializable attributes
+                    continue;
+                }
+                throw wae;
+            }
             attributes.put(name, value);
         }
         isValid = isValidSave;
@@ -871,9 +879,7 @@
             try {
                 stream.writeObject(saveValues.get(i));
             } catch (NotSerializableException e) {
-                log.error(sm.getString("standardSession.notSerializable",saveNames.get(i), id), e);
-                stream.writeObject(NOT_SERIALIZED);
-                log.error("  storing attribute '" + saveNames.get(i)+ "' with value NOT_SERIALIZED");
+                log.error(sm.getString("standardSession.notSerializable", saveNames.get(i), id), e);
             }
         }
 
Index: java/org/apache/catalina/session/StandardSession.java
===================================================================
--- java/org/apache/catalina/session/StandardSession.java	(revision 1703678)
+++ java/org/apache/catalina/session/StandardSession.java	(working copy)
@@ -22,6 +22,7 @@
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.io.WriteAbortedException;
 import java.security.AccessController;
 import java.security.Principal;
 import java.security.PrivilegedAction;
@@ -113,6 +114,7 @@
     // ----------------------------------------------------------- Constructors
 
 
+    
     /**
      * Construct a new Session associated with the specified Manager.
      *
@@ -141,14 +143,6 @@
 
 
     /**
-     * The dummy attribute value serialized when a NotSerializableException is
-     * encountered in <code>writeObject()</code>.
-     */
-    protected static final String NOT_SERIALIZED =
-        "___NOT_SERIALIZABLE_EXCEPTION___";
-
-
-    /**
      * The collection of user data attributes associated with this Session.
      */
     protected Map<String, Object> attributes = new ConcurrentHashMap<>();
@@ -1631,9 +1625,16 @@
         isValid = true;
         for (int i = 0; i < n; i++) {
             String name = (String) stream.readObject();
-            Object value = stream.readObject();
-            if ((value instanceof String) && (value.equals(NOT_SERIALIZED)))
-                continue;
+            final Object value;
+            try {
+                value = stream.readObject();
+            } catch (WriteAbortedException wae) {
+                if (wae.getCause() instanceof NotSerializableException) {
+                    // Skip non serializable attributes
+                    continue;
+                }
+                throw wae;
+            }
             if (manager.getContext().getLogger().isDebugEnabled())
                 manager.getContext().getLogger().debug("  loading attribute '" + name +
                     "' with value '" + value + "'");
@@ -1709,18 +1710,11 @@
             try {
                 stream.writeObject(saveValues.get(i));
                 if (manager.getContext().getLogger().isDebugEnabled())
-                    manager.getContext().getLogger().debug
-                        ("  storing attribute '" + saveNames.get(i) +
-                        "' with value '" + saveValues.get(i) + "'");
+                    manager.getContext().getLogger().debug(
+                            "  storing attribute '" + saveNames.get(i) + "' with value '" + saveValues.get(i) + "'");
             } catch (NotSerializableException e) {
-                manager.getContext().getLogger().warn
-                    (sm.getString("standardSession.notSerializable",
-                     saveNames.get(i), id), e);
-                stream.writeObject(NOT_SERIALIZED);
-                if (manager.getContext().getLogger().isDebugEnabled())
-                    manager.getContext().getLogger().debug
-                       ("  storing attribute '" + saveNames.get(i) +
-                        "' with value NOT_SERIALIZED");
+                manager.getContext().getLogger()
+                        .warn(sm.getString("standardSession.notSerializable", saveNames.get(i), id), e);
             }
         }
 
Index: test/org/apache/catalina/session/TestStandardSession.java
===================================================================
--- test/org/apache/catalina/session/TestStandardSession.java	(revision 1703678)
+++ test/org/apache/catalina/session/TestStandardSession.java	(working copy)
@@ -26,9 +26,7 @@
 import java.util.Map;
 
 import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Test;
-
 import org.apache.catalina.Manager;
 import org.apache.catalina.core.StandardContext;
 
@@ -93,19 +91,29 @@
     }
 
 
+    /**
+     * See Bug 58284
+     */
     @Test
-    @Ignore // This currently fails on de-serialization - bug 58284
-    public void testSerializationComplex01() throws Exception {
+    public void serializeSkipsNonSerializableAttributes() throws Exception {
+        final String nonSerializableKey = "nonSerializable";
+        final String nestedNonSerializableKey = "nestedNonSerializable";
+        final String serializableKey = "serializable";
+        final Object serializableValue = "foo";
 
         StandardSession s1 = new StandardSession(TEST_MANAGER);
         s1.setValid(true);
-        Map<String,NonSerializable> value = new HashMap<>();
+        Map<String, NonSerializable> value = new HashMap<>();
         value.put("key", new NonSerializable());
-        s1.setAttribute("attr01", value);
+        s1.setAttribute(nestedNonSerializableKey, value);
+        s1.setAttribute(serializableKey, serializableValue);
+        s1.setAttribute(nonSerializableKey, new NonSerializable());
 
         StandardSession s2 = serializeThenDeserialize(s1);
 
-        validateSame(s1, s2, 0);
+        Assert.assertNull(s2.getAttribute(nestedNonSerializableKey));
+        Assert.assertNull(s2.getAttribute(nonSerializableKey));
+        Assert.assertEquals(serializableValue, s2.getAttribute(serializableKey));
     }
 
 
@@ -142,4 +150,4 @@
 
     private static class NonSerializable {
     }
-}
+}
\ No newline at end of file