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Charge your APIs Volume 19: Understanding Problem Details for HTTP APIs - A Deep Dive into RFC 7807 and RFC 9457

30.11.2023 | 15 minutes of reading time

In today's ever-changing web development landscape, HTTP APIs have become indispensable, powering a myriad of applications and services across the internet. They act as the vital communication backbone, enabling smooth data exchanges between different systems. However, an ongoing challenge in this area is efficient error handling. How should APIs convey problems? And how can developers make sure that their error messages are not only useful and standardised but also easily understood? Enter the concept of "Problem Details for HTTP APIs," as defined in RFC 7807 – a crucial tool in this context.

RFC 7807, a standard that provides a method for conveying machine-readable error details in an HTTP response, has revolutionised the field. This standard eliminates the need to create new error response formats for HTTP APIs, offering a uniform way to send error information from servers to clients. This method simplifies the error-handling process for developers and improves the overall user experience by delivering error information that is clear, consistent, and actionable.

The more recent introduction of RFC 9457 has added new dimensions and updates to this framework. Building on the groundwork laid by RFC 7807, RFC 9457 further develops and fine-tunes these concepts, ensuring the standards evolve alongside the needs of modern web applications. Together, these documents provide a comprehensive set of guidelines for managing errors in HTTP APIs – an often-neglected but essential aspect of creating resilient and user-friendly web services.

In this blog post, we're going to take a deep dive into the details of RFC 7807 and RFC 9457. We'll explore their importance, how they're implemented, and the significant impact they have on both the design and usage of HTTP APIs. From understanding the basic structure of a problem detail object to keeping up with the latest updates and best practices, our goal is to offer an in-depth understanding of these standards and their crucial role in the future of API development. Whether you're an API developer, a provider of web services, or simply interested in the nuances of web communication, this exploration into HTTP API error handling is set to be informative and highly practical.

RFC 7807 - Basics and Importance

The introduction of RFC 7807 was a game-changer in the world of HTTP APIs. This standard, known as "Problem Details for HTTP APIs," revolutionised the way error conditions are represented in HTTP operations. In an environment where dealing with a myriad of error formats is the norm, this standardisation is a lifesaver, making the often arduous tasks of debugging and resolving issues much more manageable.

At the heart of RFC 7807 is its innovative approach to error handling. Normally, when an API hits a snag, it shoots back an error response. The catch is, these responses can vary wildly in format, depending on how the API is designed. This variability can be a real headache, especially for developers juggling multiple APIs. RFC 7807 tackles this head-on by introducing a uniform format for these error responses, ensuring they’re easy to read and process, whether you’re a human or a machine.

One of the standout features of RFC 7807 is the structure of its problem detail object. This includes several standardised fields, like a type URI to pinpoint the problem type, a title that gives a quick, readable summary of the issue, and a status code that mirrors the HTTP response status. It even has room for extra details if needed, allowing for a deeper dive into the problem or a URI to pinpoint exactly where things went south.

This structured approach brings a host of benefits to the table. For API users, it means a consistent, predictable way of handling errors across various APIs, making life a lot easier. For developers, it streamlines the whole error reporting and management process within the API. No more crafting bespoke error formats – they’ve got a standardised blueprint to follow.

But RFC 7807 isn’t just about uniformity; it’s about elevating the entire API experience. With its detailed, actionable error info, it empowers clients to really grasp what’s gone wrong and how to fix it, potentially cutting down significantly on troubleshooting time.

In essence, RFC 7807 is a cornerstone in HTTP API design and usage. Its approach to standardising error responses does more than just bring consistency and efficiency; it also makes the API world a more transparent and user-friendly place. Diving into its details and uses, it’s clear that RFC 7807 is so much more than just a set of rules; it’s a crucial ingredient for crafting robust, dependable APIs.

Deep Dive into RFC 7807

Delving into RFC 7807, we uncover a meticulously crafted approach to error handling in HTTP APIs, significantly improving the dialogue between servers and their clients when problems arise. The standard introduces the concept of "problem detail" as a means of conveying intricate, machine-readable error information in HTTP responses, eliminating the need to create new error response formats for HTTP APIs.

At the core of RFC 7807 is the Problem Details Object. This JSON object is purpose-built to deliver comprehensive error details in a standardised format. It encompasses several fields, each uniquely contributing to a clear depiction of the error's nature and how to resolve it. The type field, a URI, distinctively pinpoints the error's essence. It links to human-readable documentation that elucidates the problem type, offering an explicit understanding of the issue. The title field, akin to an error message, provides a succinct, human-readable overview of the problem, but without the usual variability seen in detailed error messages.

The status field reflects the HTTP status code the origin server produced for this specific problem instance, effectively bridging the gap between the HTTP response and the problem detail object and ensuring their alignment. Other fields like detail and instance add more layers of context. The detail field gives a human-readable description tailored to this particular problem, furnishing extra insights for diagnosis or resolution. The instance field, a URI reference, pinpoints the exact occurrence of the issue, which is invaluable for debugging, especially in large systems where pinpointing the source of an error can be daunting.

Applying RFC 7807 in APIs strikes a crucial balance: it provides enough detail to be useful without disclosing sensitive information. This approach champions transparency in error reporting while safeguarding security and privacy, a balance vital for maintaining an API's trustworthiness and usability.

Moreover, RFC 7807 paves the way for expanding problem types. With the type field being a URI, organisations can tailor their own problem types, adapting the standard to their unique scenarios. This versatility allows the standard to be broadly relevant while catering to the diverse needs of various APIs.

In essence, RFC 7807's method of managing errors in HTTP APIs is both thorough and adaptable. By standardising the format of problem detail objects, it ensures a consistent and effective communication of errors, thus boosting the overall reliability and ease of use of APIs. Its well-considered structure supports detailed, practical error reporting, key for efficient API usage and troubleshooting. As we delve into its real-world application, it's evident that RFC 7807 is an essential tool for contemporary API development, adeptly navigating the complexities of error handling with clarity and precision.

RFC 9457 - What’s New?

The roll-out of RFC 9457 marks a significant step forward in the realm of HTTP API error handling, building on the key principles set by RFC 7807. Although not as well-known as its forerunner, RFC 9457 plays a crucial role in refining and expanding the ideas introduced in RFC 7807, ensuring the standard stays up-to-date and effective amidst constantly changing tech demands.

RFC 9457 mainly aims to tackle some of the shortcomings and blind spots found in RFC 7807, especially in situations that weren’t completely addressed or foreseen in the original version. This update reflects the ongoing changes in the API landscape, a field where new challenges and needs pop up regularly, prompting the need for tweaks and improvements to the established norms.

A central feature of RFC 9457 is its emphasis on boosting the flexibility and richness of the problem detail object. It brings in fresh recommendations and enhancements that enable API developers to deliver more accurate and helpful error information. This is especially vital in intricate systems where errors can be multifaceted or need thorough explanations to be fully understood and resolved.

Moreover, RFC 9457 seeks to better the interoperability among various systems and services. With APIs increasingly becoming more interconnected, the capacity to smoothly handle and relay errors across different systems is becoming more and more essential. The updates in RFC 9457 are tailored to support this, ensuring that error handling is consistent not just within a single API, but also across multiple APIs that might interact with each other.

Additionally, RFC 9457 considers the real-world feedback and experiences of developers who have used RFC 7807. This kind of feedback loop is vital for any technical standard, as it anchors the standard in real-life use, rather than just theory. By integrating these insights, RFC 9457 doesn't just build on the existing framework but also makes it more approachable and relevant for a broader array of situations.

In short, RFC 9457 is a well-considered and necessary enhancement to the problem details standard. It improves the clarity, adaptability, and practicality of RFC 7807, making sure the standard continues to align with the demands of modern API development. As we explore the details of RFC 9457 and its impact on HTTP APIs, it's clear that this document is more than just a supplement to its predecessor; it's an important work in its own right, shaping the future of error handling in the rapidly changing world of web services.

Implementing Problem Details in Practice

Applying RFC 7807 and RFC 9457 to HTTP APIs is a nuanced process that requires a deep understanding of these standards and a thoughtful approach to error handling. This is a critical step for developers who are keen on making their APIs more robust and user-friendly. Implementing these standards effectively not only helps in pinpointing issues but also significantly enhances the developer experience during API interactions.

The journey begins with incorporating the problem details object into the API's error responses. This means moving away from the more traditional, often inconsistent error handling methods to a structured format as described in RFC 7807. Developers need to ensure their APIs deliver error messages in this standardised format, complete with key fields like type, title, and status. These elements are crucial in making error messages informative, actionable, and consistent across various endpoints and services.

The detail and instance fields in particular offer developers a chance to provide more specific context about an error. This is where the real strength of the problem details object shines, as it enables the delivery of detailed and actionable error information, drastically cutting down on the time and effort needed for troubleshooting.

However, adopting these standards is not without its challenges. A significant consideration is striking the right balance between giving enough detail in the error messages and safeguarding sensitive information. Developers must be meticulous in deciding what information goes into the problem details object to avoid revealing internal processes or sensitive data, which could pose security risks.

Furthermore, tailoring the problem types to fit an organisation's unique needs, as permitted by RFC 9457, calls for careful planning. Developers should create custom problem types that precisely reflect their API's specific errors, ensuring these types are well-documented and easily comprehensible to API users.

In practice, integrating RFC 7807 and RFC 9457 can be a learning process, particularly for teams more accustomed to conventional error handling methods. This transition can be smoothed over with thorough documentation, training, and possibly the use of middleware or libraries that simplify the complexity involved in structuring error responses according to these standards.

In essence, successfully implementing RFC 7807 and RFC 9457 in HTTP APIs is a testament to adhering to the best practices in API design. It demonstrates an organisation's commitment to providing clear, consistent, and meaningful error information, a key indicator of top-tier, user-focused API development. As developers work through the nuances of these standards and apply them to their APIs, they play a part in creating a more dependable and efficient digital ecosystem, transforming errors from mere obstacles into valuable learning and information tools.

Example: Fetching a Non-Existing Book

Client Request:

1GET /api/books/12345 HTTP/1.1

Server Response:

1HTTP/1.1 404 Not Found
2Content-Type: application/problem+json
3Content-Language: en
6  "type": "",
7  "title": "Book Not Found",
8  "status": 404,
9  "detail": "The book with ID 12345 could not be found in our database.",
10  "instance": "/api/books/12345",
11  "timestamp": "2023-11-28T12:34:56Z",
12  "custom-field": "Additional information or context here"


  • type: A URI reference that identifies the problem type. It is a URL that, when dereferenced, provides human-readable documentation about the problem. In this case, it points to a "book-not-found" type, suggesting the nature of the problem.
  • title: A short, human-readable summary of the problem type. It does not vary for different occurrences of the problem and is designed to be used in conjunction with the type field.
  • status: The HTTP status code generated by the server for this occurrence of the problem. It matches the status code in the HTTP response.
  • detail: A human-readable explanation specific to this occurrence of the problem. It provides a more detailed message which can assist in diagnosing or fixing the issue.
  • instance: A URI reference that identifies the specific occurrence of the problem. It can be helpful for logging purposes or for providing more context in larger systems.
  • timestamp (RFC 9457 enhancement): A timestamp indicating when the problem was generated. This helps in logging and tracing the error, especially in systems where timing is critical.
  • custom-field: A demonstration of the extensibility of the problem detail object. Developers can add additional fields to convey more information relevant to the problem or to their specific application context.

In this example, the Problem Details object effectively communicates the nature of the error (a non-existing book), provides a specific HTTP status code (404 Not Found), and includes additional details to assist the client in understanding and addressing the issue. The inclusion of a timestamp and a custom field demonstrates the extensibility and flexibility of the standard, allowing for more contextual information per the requirements of RFC 9457.

The Future of HTTP API Error Handling

Looking forward, it's clear that HTTP API error handling is on a trajectory of continual growth and improvement, especially when considering standards like RFC 7807 and RFC 9457. This progress is shaped not only by technological advances but also by the evolving needs and expectations of both developers and end-users within the API community.

A key factor driving this evolution is the increasing complexity and interconnectedness of digital systems. As APIs become ever more crucial to the infrastructure of modern web and cloud services, the demand for more advanced error handling mechanisms becomes critical. The complexity of today's digital landscape calls for error handling that is informative, standardised, and versatile enough to adapt to different scenarios and manage complex, layered error conditions.

We're expecting to see further enhancements to these existing standards. These could include more nuanced classifications of error types, better support for internationalisation and localisation to serve a global audience, and tighter integration with cutting-edge technologies like machine learning and AI. Such advancements could automate aspects of error detection and resolution, bolstering the robustness and independence of APIs.

Equally important is the role of the community and open-source contributions in shaping the future of API error handling. The ongoing development and refinement of standards like RFC 7807 and RFC 9457 aren't just in the hands of official bodies; they heavily depend on input, practical use cases, and contributions from the developer community. This collaborative effort ensures that these standards stay relevant, effective, and responsive to the actual challenges developers face.

Additionally, there's an increasing awareness of the significance of user-centric design in API development, encompassing error handling as well. Future developments are likely to focus on making APIs clearer, more user-friendly, and accessible, catering to a wide array of users, including those without extensive technical background.

In summary, the future of HTTP API error handling looks set to become more dynamic, collaborative, and centred around the user. As technology progresses and the needs of the digital ecosystem expand, standards like RFC 7807 and RFC 9457 will remain essential in guiding how APIs communicate errors. The continuous evolution of these standards highlights the growing importance of APIs in our digital world and the collective commitment to making them more reliable, efficient, and accessible to everyone.


As we wrap up our deep dive into Problem Details for HTTP APIs, as outlined in RFC 7807 and further refined in RFC 9457, it's evident that these standards are much more than mere technicalities. They mark a significant shift towards a more structured, transparent, and user-friendly approach in handling API errors. This progression is vital in the wider context of API development and use, where clear and consistent error reporting is key to efficient operation and user satisfaction.

The role of RFC 7807 and RFC 9457 in modern API development is crucial. By establishing a standardised format for error responses, these documents tackle a widespread issue in API interactions: the unpredictability and inconsistency of error messages. This standardisation not only simplifies things for developers, who can now expect a consistent error response structure across different APIs, but it also benefits end-users with more informative and actionable error information.

The tech community's embrace of these standards signals a recognition of the need for improved error handling practices. It acknowledges that effective error communication is just as important as the API's functionality. This move towards better error handling isn't just about following a set of rules; it's about adopting a philosophy that values transparency, dependability, and a focus on the user in technology.

Looking ahead, the ongoing evolution of these standards, fuelled by technological progress and feedback from the community, promises further enhancements and refinements. As APIs become ever more crucial to our digital infrastructure, the manner in which they report and manage errors will continue to play a pivotal role in their usability and effectiveness.

In summing up, RFC 7807 and RFC 9457 go beyond serving as mere guidelines; they act as drivers of change in the API landscape. They push developers and organisations to prioritise effective error handling, leading to stronger, more user-friendly APIs. As the digital world keeps evolving, the principles established by these standards will undoubtedly keep influencing and shaping API development, ensuring that APIs are not only functional but also clear and accessible to all.

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