diff --git a/odoo/addons/base/tests/test_translate.py b/odoo/addons/base/tests/test_translate.py
index 24fa1597515..12c3f8b2d96 100644
--- a/odoo/addons/base/tests/test_translate.py
+++ b/odoo/addons/base/tests/test_translate.py
@@ -479,7 +479,29 @@ class TestTranslationWrite(TransactionCase):
             {'src': 'English Name', 'value': 'English Name', 'lang': 'en_US'},
             {'src': 'English Name', 'value': 'French Name', 'lang': 'fr_FR'}
         ])
-      
+
+    def test_04_fr_multi_no_en(self):
+        self.env['res.lang'].load_lang('fr_FR')
+        self.env['res.users'].with_context(active_test=False).search([]).write({'lang': 'fr_FR'})
+        self.env['res.lang'].load_lang('es_ES')
+        self.env.ref('base.lang_en').active = False
+
+        langs = self.env['res.lang'].get_installed()
+        self.assertEqual([('fr_FR', 'French / Français'), ('es_ES', 'Spanish / Español')], langs,
+                         "Test did not start with the expected languages")
+
+        self.category.with_context(lang='fr_FR').write({'name': 'French Name'})
+        self.category.with_context(lang='es_ES').write({'name': 'Spanish Name'})
+        self.category.with_context(lang=None).write({'name': 'None Name'})
+
+        translations = self.env['ir.translation'].search([
+            ('name', '=', 'res.partner.category,name'),
+            ('res_id', '=', self.category.id),
+        ], order='lang')
+        self.assertRecordValues(translations, [
+            {'src': 'None Name', 'value': 'Spanish Name', 'lang': 'es_ES'},
+            {'src': 'None Name', 'value': 'French Name', 'lang': 'fr_FR'},
+        ])
 
     def test_05_remove_multi(self):
         self.env['res.lang'].load_lang('fr_FR')
diff --git a/odoo/fields.py b/odoo/fields.py
index 1eaaeb4a2a1..70dadd84850 100644
--- a/odoo/fields.py
+++ b/odoo/fields.py
@@ -1439,7 +1439,7 @@ class _String(Field):
         update_trans = False
         single_lang = len(records.env['res.lang'].get_installed()) <= 1
         if self.translate:
-            lang = records.env.lang or 'en_US'
+            lang = records.env.lang or None  # used in _update_translations below
             if single_lang:
                 # a single language is installed
                 update_trans = True
@@ -1447,10 +1447,11 @@ class _String(Field):
                 # update the source and synchronize translations
                 update_column = True
                 update_trans = True
-            elif lang != 'en_US':
+            elif lang != 'en_US' and lang is not None:
                 # update the translations only except if emptying
                 update_column = cache_value is None
                 update_trans = True
+            # else: lang = None
 
         # update towrite if modifying the source
         if update_column:
@@ -1461,6 +1462,7 @@ class _String(Field):
             if self.translate is True and cache_value is not None:
                 tname = "%s,%s" % (records._name, self.name)
                 records.env['ir.translation']._set_source(tname, real_recs._ids, value)
+                records.invalidate_cache(fnames=[self.name], ids=records.ids)
 
         if update_trans:
             if callable(self.translate):
@@ -1471,7 +1473,7 @@ class _String(Field):
             else:
                 # update translations
                 value = self.convert_to_column(value, records)
-                source_recs = real_recs.with_context(lang='en_US')
+                source_recs = real_recs.with_context(lang=None)
                 source_value = first(source_recs)[self.name]
                 if not source_value:
                     source_recs[self.name] = value