diff --git a/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/introspector/JsonTypeAndClassAnnotationIntrospector.java b/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/introspector/JsonTypeAndClassAnnotationIntrospector.java
index fb76746dade2c2627e577b748918154f4b197e87..b27735b9dda230dd47b91299d230b3ebac4125b6 100644
--- a/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/introspector/JsonTypeAndClassAnnotationIntrospector.java
+++ b/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/introspector/JsonTypeAndClassAnnotationIntrospector.java
@@ -87,7 +87,8 @@ public class JsonTypeAndClassAnnotationIntrospector extends JacksonAnnotationInt
 
     private boolean useCustomResolver(JavaType type)
     {
-        return type.getRawClass().isAnnotationPresent(JsonObject.class) && false == type.getRawClass().isEnum();
+        return type.getRawClass().equals(Object.class)
+                || (type.getRawClass().isAnnotationPresent(JsonObject.class) && false == type.getRawClass().isEnum());
     }
 
 }
diff --git a/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/serializer/JsonSerializerFactory.java b/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/serializer/JsonSerializerFactory.java
index d1d5518bb2079ab0805b104ecf1a8521a427902c..f561dcca0a38e6d6fffafe8a8b68c7c37e2731b5 100644
--- a/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/serializer/JsonSerializerFactory.java
+++ b/openbis-common/source/java/ch/systemsx/cisd/openbis/common/api/server/json/serializer/JsonSerializerFactory.java
@@ -102,7 +102,7 @@ public class JsonSerializerFactory extends BeanSerializerFactory
 
         Class<?> contentClass = contentType.getRawClass();
 
-        if (contentClass.isAnnotationPresent(JsonObject.class) && false == contentClass.isEnum())
+        if (contentClass.equals(Object.class) || (contentClass.isAnnotationPresent(JsonObject.class) && false == contentClass.isEnum()))
         {
             BeanDescription bean = config.introspectClassAnnotations(contentType.getRawClass());
             AnnotatedClass ac = bean.getClassInfo();