Support Team replied the topic: OAuthException: An unexpected error has occurred.
If you want to avoid errors in Facebook App Insights, you have to change Media mode="Status message only". In this way no links or images are included in Posts. So, no error is returned when the Post is published.
As errors are only generated in some Apps posting to Pages, we are going to keep creating full Posts by default, with these settings to avoid duplication or false positives.