I need help with error handling patterns for my REST API project. Currently I’m using XML format but will add JSON support later.
Right now I handle basic errors with HTTP status codes like 401 for auth issues, 403 for permissions, and 404 for bad URLs. But I’m stuck on application-specific errors. For example, when a user tries to create a resource but has hit their storage limit.
I looked at HTTP status codes in the 400-417 range but none seem perfect for business logic errors. My first idea was to return 200 OK with error details in the XML response body, but that feels wrong and inconsistent with my other error handling.
What’s the standard approach for this? Should I stick to HTTP status codes only or mix them with response body errors? I want to make it easy for client developers to work with my API. Any recommendations on best practices would be great.
For business logic errors like storage limits, I recommend using a 400 Bad Request status code along with detailed error information in the response body. The client’s request may be considered invalid based on the current business state, making this approach sensible. It’s crucial to maintain consistency—each response should include both machine-readable error codes and user-friendly messages, formatted in XML. I’ve experienced that using varying status codes for similar violations complicates client-side integration. When transitioning to JSON, ensure to adhere to the same error schema for uniformity across formats. Additionally, it’s beneficial to provide contextual information such as current usage, as client developers will find that extremely useful.
I’ve hit this before - 409 Conflict is perfect for business constraint violations like storage limits. Just stay consistent with your HTTP status codes and always include structured error details in the response body. For storage limits, return 409 with XML that has the error code, message, and useful stuff like current usage or how much they went over. Client developers can handle errors programmatically this way, and you’re following proper HTTP semantics. When you add JSON later, use the same structure and status codes so everything stays consistent.
422 unprocessable entity is perfect for biz logic failures like storage limits. It’s clear for devs. Don’t return 200 with error details - that breaks HTTP conventions and confuses clients checkin status codes first.