diff --git a/locale/es.po b/locale/es.po
index 7853916..3752da8 100644
--- a/locale/es.po
+++ b/locale/es.po
@@ -2,21 +2,21 @@
 msgid ""
 msgstr "Content-Type: text/plain; charset=utf-8\n"
 
-msgctxt "error:stock.lot.replace:"
+msgctxt "model:ir.message,text:msg_lot_period_cache"
 msgid ""
-"Cannot replace lots with Period cache. Please go back period \"%s\" to Draft"
+"Cannot replace lots with Period cache. Please go back period \"%(period)s\" to Draft"
 " first."
-msgstr "No puede reemplazar lotes usados en Períodos. Ponga primero estado Borrador en período \"%s\"."
+msgstr "No puede reemplazar lotes usados en Períodos. Ponga primero estado Borrador en período \"%(period)s\"."
 
-msgctxt "error:stock.lot.replace:"
+msgctxt "model:ir.message,text:msg_lot_different_name"
 msgid "Lots have different numbers: %(source_name)s vs %(destination_name)s."
 msgstr "Los lotes tienen números diferentes: %(source_name)s vs %(destination_name)s."
 
-msgctxt "error:stock.lot.replace:"
+msgctxt "model:ir.message,text:msg_lot_different_product"
 msgid "Lots have different product: %(source_code)s vs %(destination_code)s."
 msgstr "Los lotes tienen productos diferentes: %(source_code)s vs %(destination_code)s."
 
-msgctxt "error:stock.lot:"
+msgctxt "model:ir.message,text:msg_lot_uniq_by_product"
 msgid "Lot number must be unique by product."
 msgstr "Número de lote debe ser único por Producto."
 
diff --git a/message.xml b/message.xml
new file mode 100644
index 0000000..f12c3ee
--- /dev/null
+++ b/message.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<!-- The COPYRIGHT file at the top level of this repository contains the full
+     copyright notices and license terms. -->
+<tryton>
+    <data grouped="1">
+        <record model="ir.message" id="msg_lot_different_name">
+            <field name="text">Lots have different numbers: %(source_name)s vs %(destination_name)s.</field>
+        </record>
+        <record model="ir.message" id="msg_lot_different_product">
+            <field name="text">Lots have different product: %(source_code)s vs %(destination_code)s.</field>
+        </record>
+        <record model="ir.message" id="msg_lot_period_cache">
+            <field name="text">Cannot replace lots with Period cache. Please go back period "%(period)s" to Draft first.</field>
+        </record>
+        <record model="ir.message" id="msg_lot_uniq_by_product">
+            <field name="text">Lot number must be unique by product.</field>
+        </record>
+    </data>
+</tryton>
\ No newline at end of file
diff --git a/stock.py b/stock.py
index ed3d9bf..bbf5ee0 100644
--- a/stock.py
+++ b/stock.py
@@ -6,8 +6,8 @@ from trytond.pool import PoolMeta, Pool
 from trytond.pyson import Eval
 from trytond.transaction import Transaction
 from trytond.wizard import Wizard, StateView, StateTransition, Button
-
-__all__ = ['Lot', 'LotReplace', 'LotReplaceAsk']
+from trytond.exceptions import UserError, UserWarning
+from trytond.i18n import gettext
 
 
 class Lot(metaclass=PoolMeta):
@@ -19,7 +19,7 @@ class Lot(metaclass=PoolMeta):
         t = cls.__table__()
         cls._sql_constraints += [
             ('lot_uniq', Unique(t, t.number, t.product),
-                'Lot number must be unique by product.'),
+                'stock_lot_unique.msg_lot_uniq_by_product'),
         ]
 
 
@@ -35,36 +35,26 @@ class LotReplace(Wizard):
             ])
     replace = StateTransition()
 
-    @classmethod
-    def __setup__(cls):
-        super(LotReplace, cls).__setup__()
-        cls._error_messages.update({
-            'different_name':
-                'Lots have different numbers: '
-                '%(source_name)s vs %(destination_name)s.',
-            'different_product':
-                'Lots have different product: '
-                '%(source_code)s vs %(destination_code)s.',
-            'period_cache': 'Cannot replace lots with Period cache. '
-                'Please go back period "%s" to Draft first.'
-        })
-
     def check_similarity(self):
+        pool = Pool()
+        Warning = pool.get('res.user.warning')
+
         sources = self.ask.sources
         destination = self.ask.destination
         for source in sources:
             if source.number != destination.number:
                 key = 'stock.lot.replace number %s %s' % (
                     source.number, destination.number)
-                self.raise_user_warning(key, 'different_name', {
-                        'source_name': source.number,
-                        'destination_name': destination.number,
-                        })
+                if Warning.check(key):
+                    raise UserWarning(key, gettext(
+                        'stock_lot_unique.msg_lot_different_name',
+                        source_name=source.number,
+                        destination_name=destination.number))
             if source.product.id != destination.product.id:
-                self.raise_user_error('different_product', {
-                        'source_code': source.product.rec_name,
-                        'destination_code': destination.product.rec_name,
-                        })
+                raise UserError(gettext(
+                    'stock_lot_unique.msg_lot_different_product',
+                    source_code=source.product.rec_name,
+                    destination_code=destination.product.rec_name))
 
     def check_period_cache(self):
         pool = Pool()
@@ -73,7 +63,9 @@ class LotReplace(Wizard):
         lot_ids = [s.id for s in self.ask.sources] + [self.ask.destination.id]
         caches = Cache.search([('lot', 'in', lot_ids)], limit=1)
         if caches:
-            self.raise_user_error('period_cache', caches[0].period.rec_name)
+            raise UserError(gettext(
+                'stock_lot_unique.msg_lot_period_cache',
+                period=caches[0].period.rec_name))
 
     def transition_replace(self):
         pool = Pool()
diff --git a/tests/scenario_lot_replace.rst b/tests/scenario_lot_replace.rst
index 8f28946..93f266d 100644
--- a/tests/scenario_lot_replace.rst
+++ b/tests/scenario_lot_replace.rst
@@ -32,17 +32,15 @@ Create product::
 
     >>> ProductUom = Model.get('product.uom')
     >>> ProductTemplate = Model.get('product.template')
-    >>> Product = Model.get('product.product')
     >>> unit, = ProductUom.find([('name', '=', 'Unit')])
-    >>> product = Product()
     >>> template = ProductTemplate()
     >>> template.name = 'Product'
     >>> template.default_uom = unit
     >>> template.type = 'goods'
     >>> template.list_price = Decimal('20')
-    >>> template.cost_price = Decimal('8')
     >>> template.save()
-    >>> product.template = template
+    >>> product, = template.products
+    >>> product.cost_price = Decimal('8')
     >>> product.save()
 
 Get stock locations::
@@ -129,10 +127,10 @@ Replace the second by the first lot::
     True
     >>> replace.form.destination == lot1
     True
-    >>> replace.execute('replace') # doctest: +IGNORE_EXCEPTION_DETAIL
+    >>> replace.execute('replace')
     Traceback (most recent call last):
         ...
-    UserWarning: ('UserWarning', ('stock.lot.replace nmber 2 1', u'Lots have different numbers: L-1 vs L1.', ''))
+    trytond.exceptions.UserWarning: Lots have different numbers: L-1 vs L1. - 
 
     >>> Model.get('res.user.warning')(user=config.user,
     ...     name='stock.lot.replace number L-1 L1', always=True).save()
diff --git a/tests/test_stock_lot_unique.py b/tests/test_stock_lot_unique.py
index e33832f..5c13f80 100644
--- a/tests/test_stock_lot_unique.py
+++ b/tests/test_stock_lot_unique.py
@@ -30,7 +30,6 @@ class StockLotUniqueTestCase(ModuleTestCase):
             'name': 'Test Move.internal_quantity',
             'type': 'goods',
             'list_price': Decimal(1),
-            'cost_price': Decimal(0),
             'cost_price_method': 'fixed',
             'default_uom': kg.id,
         }])
diff --git a/tryton.cfg b/tryton.cfg
index a4a6c43..d8b6a05 100644
--- a/tryton.cfg
+++ b/tryton.cfg
@@ -7,3 +7,4 @@ depends:
 
 xml:
 	stock.xml
+    message.xml