Strange exception updating record

Hi guys,
all update methods in my application do well, except one. Running following code:

if ($model->loadAll(Yii::$app->request->post()) && $model->saveAll()) {

will throw out following exeption:

Unable to locate message source for category 'mtrelt'.
It’s class * vendor\yiisoft\yii2\i18n\I18N* which throws out this error. I have absolutely no idea how to fix this. Any ideas?

I fixed problem using following code

  if ($model->loadAll(Yii::$app->request->post())) {