diff --git a/news/305.bugfix b/news/305.bugfix
new file mode 100644
index 00000000..28a784a1
--- /dev/null
+++ b/news/305.bugfix
@@ -0,0 +1,6 @@
+in custom_migration.migrate the form_dx_typename should contain _space_  to match the dx_key
+
+the getDXFields javascript function doesn't replace all space in at_typename,
+causing forms to non load right fields list, or not load it at all.
+
+[gianniftp]
\ No newline at end of file
diff --git a/plone/app/contenttypes/migration/custom_migration.pt b/plone/app/contenttypes/migration/custom_migration.pt
index 7d19a2cb..33509240 100644
--- a/plone/app/contenttypes/migration/custom_migration.pt
+++ b/plone/app/contenttypes/migration/custom_migration.pt
@@ -41,7 +41,7 @@
     <script type="text/javascript">
         // function that toggle an icon by calling the p_viewName view
         function getDXFields(at_typename, dx_typename) {
-          at_safe = at_typename.replace(' ', '_space_');
+          at_safe = at_typename.replaceAll(' ', '_space_');
           $.ajax({
             url: '@@display_dx_fields',
             dataType: 'html',
diff --git a/plone/app/contenttypes/migration/custom_migration.py b/plone/app/contenttypes/migration/custom_migration.py
index 2cfdabb1..85ad7fda 100644
--- a/plone/app/contenttypes/migration/custom_migration.py
+++ b/plone/app/contenttypes/migration/custom_migration.py
@@ -63,7 +63,8 @@ def __call__(self):
                     raw_message = 'Migration applied successfully for {0} ' \
                         '"{1}" items.'
                     msg = translate(
-                        raw_message.format(res_infos.get('counter'), res_type),
+                        raw_message.format(
+                            res_infos.get('counter'), res_type),
                         domain='plone.app.contenttypes',
                     )
                     messages.add(msg, type=u'info')
@@ -165,14 +166,15 @@ def getFieldsForATTypeWithFTI(self, typename):
             return results
         for field in schema.fields():
             if not field.getName() in self.at_metadata_fields:
-                translated_label = translate(safe_unicode(field.widget.label))
+                translated_label = translate(
+                    safe_unicode(field.widget.label))
                 results.append(
                     {'id': field.getName(),
                      'title': '{0} ({1})'.format(
                          translated_label,
                          field.getType()
-                     ),
-                     'type': field.getType()}
+                    ),
+                        'type': field.getType()}
                 )
         return results
 
@@ -199,8 +201,8 @@ def getFieldsForATTypeWithoutFTI(self, typename):
                      'title': '{0} ({1})'.format(
                          translated_label,
                          field.getType()
-                     ),
-                     'type': field.getType()}
+                    ),
+                        'type': field.getType()}
                 )
         return results
 
@@ -257,6 +259,8 @@ def migrate(self, dry_run=False):
                 form_dx_typename = form[k]
                 at_typename = form_at_typename.replace('_space_', ' ')
                 dx_typename = form_dx_typename.replace('_space_', ' ')
+                # the form_dx_typename should contain _space_  to match the dx_key
+                form_dx_typename.replace(' ', '_space_')
 
                 data[at_typename] = {'target_type': dx_typename,
                                      'field_mapping': []}
@@ -296,7 +300,7 @@ def migrate(self, dry_run=False):
                 dst_type=data[at_typename]['target_type'],
                 dry_run=dry_run,
                 patch_searchabletext=patch_searchabletext,
-                )
+            )
             migration_results.append({'type': at_typename,
                                       'infos': res})
         return migration_results