Retrieve Conversation from Facebook Graph Error Code 2

I manage several Businesses and Pages.

When requesting the API for conversations I get an error for some pages and success for other pages.

The endpoint I'm requesting is: https://graph.facebook.com/v20.0/${page_id}/conversations?access_token=${access_token}&fields=${fields}

Fields:

name,id,updated_time,messages{created_time,from,id,message,attachments.limit(10) {file_url,video_data,size,name,mime_type,image_data,id,generic_template},to},participants

(Changing API version does not change the outcome).

The error that I'm receiving is:

{ "message": "An unexpected error has occurred. Please retry your request later.", "type": "OAuthException", "is_transient": true, "code": 2, "fbtrace_id": "Ak6OZA72-efdE-2Ko9NqSgy" } 

Graph Explorer returns the same error/result for the specific pages. Some returns conversations while other return the mentioned error.

Does anyone know what causes these errors?

I haven't made any changes to my code. The request was consistently working for a while, but recently it started giving these errors for some pages.

Earlier Facebook Graph API would always return conversations as expected.