Fixed payment settings form validation

src/pretix/control/forms/event.py

@@ -241,16 +241,18 @@ class ProviderForm(SettingsForm):
             v.required = False
             v.widget.is_required = False
             if isinstance(v, I18nFormField):
+                v._required = v.one_required
+                v.one_required = False
                 v.widget.enabled_langcodes = self.obj.settings.get('locales')
 
     def clean(self):
         cleaned_data = super().clean()
-        enabled = cleaned_data.get(self.settingspref + '_enabled') == 'True'
+        enabled = cleaned_data.get(self.settingspref + '_enabled')
         if not enabled:
             return
         for k, v in self.fields.items():
             val = cleaned_data.get(k)
-            if v._required and (val is None or val == ""):
+            if v._required and not val:
                 self.add_error(k, _('This field is required.'))
 
 

src/pretix/control/views/event.py

@@ -212,6 +212,7 @@ class PaymentSettings(EventPermissionRequiredMixin, TemplateView, SingleObjectMi
             messages.success(self.request, _('Your changes have been saved.'))
             return redirect(self.get_success_url())
         else:
+            messages.error(self.request, _('We could not save your changes. See below for details.'))
             return self.get(request)
 
     def get_success_url(self) -> str: