I've learned of RFC 7807 a few years ago, and as far I am aware it is the closest thing to an official standard for API error messages that we have at the moment. Its biggest drawback is that it is difficult to use casually -- because of the need for the URI identifiers it needs to be supported by an infrastructure that will categorise and identify the different problems in some kind of database.
I have been working on a small API solution that could be used to easily store and identify issues, but haven't had much time to focus on it as much as I wanted to.
I have been working on a small API solution that could be used to easily store and identify issues, but haven't had much time to focus on it as much as I wanted to.