404 Error For Api

We are having issues operating the mobile app, error logs show:

/api/4.0/sra_languages?sl=en&items_per_page=20&s_layout=6&lang_code=en¤cy=

and when trying to login to the above with username and API key as password, it causes the following 404:

{"message":"Not Found: The Entity sra_languages not found","messages":["The Entity sra_languages not found"],"status":404}

Anyone been through a similar situation to this? We really would like to get the app up and running!