diff --git a/media/forms.py b/media/forms.py
index 24b5cbd..e0e29e1 100644
--- a/media/forms.py
+++ b/media/forms.py
@@ -60,6 +60,8 @@ class MediaAdminForm(ModelForm):
         """
         If user fetch ISBN data, then download data before validating the form
         """
+        super().clean()
+
         # TODO implement authors, side_identifier
         if "_continue" in self.request.POST:
             isbn = self.cleaned_data.get('isbn')
@@ -70,4 +72,25 @@ class MediaAdminForm(ModelForm):
                     # Try with OpenLibrary
                     self.download_data_openlibrary(isbn)
 
-        return super().clean()
+        return self.cleaned_data
+
+    def _clean_fields(self):
+        for name, field in self.fields.items():
+            # value_from_datadict() gets the data from the data dictionaries.
+            # Each widget type knows how to retrieve its own data, because some
+            # widgets split data over several HTML fields.
+            if field.disabled:
+                value = self.get_initial_for_field(field, name)
+            else:
+                value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
+            from django.core.exceptions import ValidationError
+            try:
+                # We don't want to check a field when we enter an ISBN.
+                if "_continue" not in self.request.POST or not self.cleaned_data.get('isbn'):
+                    value = field.clean(value)
+                self.cleaned_data[name] = value
+                if hasattr(self, 'clean_%s' % name):
+                    value = getattr(self, 'clean_%s' % name)()
+                    self.cleaned_data[name] = value
+            except ValidationError as e:
+                self.add_error(name, e)