Navigating Failed API Requests: Understanding, Resolving, and Preventing Issues with

Navigating Failed API Requests: Understanding, Resolving, and Preventing Issues with

This guide takes developers on a journey through the complexities of API requests and responses. Explore the anatomy of API requests, decipher responses, and dissect common causes of failures. Real-world examples featuring Salesforce, Twilio, and others provide practical insights. Discover best practices and leverage for optimal API management. Elevate your API interactions with advanced strategies and a game-changing API consumption management platform.

Sean Keegan, Head of DevRel

Sean Keegan, Head of DevRel

February 1, 2024

Failed Requests

Rate Limits


From managing APIs for LLMs to business critical APIs like Salesforce or Hubspot, a failed request challenges even the best integration, often putting it to the test without any warning. Good prep is like using a "wet-floor-sign" and can get us far in reducing errors to zero, and maintaining a healthy integration. This comprehensive guide aims to unravel the complexities behind these failures, presenting practical solutions and preventive strategies. Additionally, we delve into how's innovative API consumption management platform can transform these challenges into efficient, streamlined processes.

The Intricacies of API Requests and Responses

In the dynamic world of API interactions, developers need a solid grip on the essentials that shape request and response success. Before we dive into the intricacies of API anatomy, let's refresh our minds on what demands our attention for fluid communication.

Exploring the Anatomy of API Requests

Endpoint Details:

  • The endpoint is the URL where the API service is accessed.
  • Example: In a weather forecasting application, an endpoint like would provide weather data.
  • Precision in specifying endpoints is crucial for the success of API calls.

Understanding HTTP Methods:

  • These methods (GET, POST, PUT, DELETE) define the action to be performed.
  • Each method has its protocol and is suited for specific operations, such as retrieving data (GET) or submitting new entries (POST).

The Role of Headers:

  • Headers in API requests carry critical information like content types and authorization details.
  • Misconfigured headers can lead to a variety of issues, including “bad API responses” and rejected requests due to authentication failures or content type mismatches.

Significance of the Body:

  • In methods like POST or PUT, the body of the request carries the data payload, typically in formats like JSON or XML.
  • Incorrectly structured data in the body is a frequent cause of request failures, especially when dealing with complex data structures or large payloads.

Deciphering API Responses

Navigating Status Codes:

  • These codes provide immediate feedback on the outcome of an API request.
  • Example codes: 200 for successful requests, 404 for not found errors, or 500 for server-side errors.
  • A deep understanding of these codes is essential for diagnosing and resolving issues swiftly.

Interpreting Headers and Body:

  • The response's headers and body contain vital information and data necessary for understanding the API's response.
  • This can include metadata about the response, pagination details, or the actual data payload.

Ready to Start your journey?

Get Early Access With Lunar and a free API Overview Report

Dissecting the Common Causes of Failed API Requests

Authentication and Authorization Errors


  • Imagine a customer relationship management (CRM) platform integrated with the Salesforce API, encountering persistent 401 Unauthorized errors. Investigation reveals an issue with an expired API token, disrupting secure access to crucial customer data.


  • Authentication and authorization errors often emerge when API requests lack valid credentials. In this case, with the Salesforce API, an expired token can hinder the CRM platform's ability to securely access and manage customer information.

How to Fix:

  • Implement token refresh mechanisms, regularly update API keys, and ensure correct and secure handling of authentication credentials.

Client-Side Mistakes


  • A team developing a language processing app utilizing the OpenAI API faces a series of 404 Not Found errors. Investigation reveals that typos in the API endpoint URLs are responsible for the communication breakdown.


  • Client-side mistakes, often denoted by 4xx status codes, can stem from errors in requests made by the client application. Typos in endpoint URLs, as seen with the OpenAI API, can lead to frequent 404 errors, impacting language processing capabilities.

How to Fix:

  • Conduct thorough code reviews, implement automated testing, and validate request formats and endpoints before deployment.

Rate Limiting and Throttling


  • A real-time analytics dashboard, heavily reliant on the Twitter API to fetch live tweet data, surpasses the API's rate limits during a trending event, resulting in failed data requests.


  • APIs employ rate limiting to control the frequency of user requests. In scenarios of high demand, such as during trending events on Twitter, exceeding these limits can trigger throttling and subsequently lead to failed data requests.

How to Fix:

  • Implement efficient request scheduling, respect API rate limits, and consider strategies like request caching or optimizing API call patterns.

Caching Errors


  • Imagine a marketing analytics dashboard integrated with the HubSpot API, displaying outdated campaign performance metrics due to a caching error. The failure to fetch new data results in users relying on stale information for strategic decision-making.


  • Caching errors occur when outdated or incorrect data is retrieved from a cache, affecting applications that rely on real-time information from APIs.

How to Fix:

  • Implement proper cache invalidation strategies, set appropriate cache lifetimes, and use conditional requests to validate cached data.

Using HTTP Instead of HTTPS


  • Consider a messaging app integrating with the Twilio API. The app sends sensitive messages over HTTP instead of the secure HTTPS, exposing users to potential data interception and security risks.


  • This error arises when API requests are made over unsecured HTTP rather than the encrypted HTTPS. In the context of the Twilio API, ensuring secure connections is vital, especially when dealing with sensitive communication data.

How to Fix:

  • Ensure all API requests are made over HTTPS to provide encryption and security. Update API endpoints and configurations to enforce HTTPS connections.

Using the Wrong HTTP Method


  • A payment processing platform integrating with the Stripe API faces a 405 Method Not Allowed error. Investigation reveals that the client application erroneously uses a GET request for processing payments instead of the required POST request.


  • This occurs when an API request utilizes an incorrect HTTP method, leading to unexpected behavior. In this case, the Stripe API expects POST requests for processing payments, highlighting the importance of adhering to API documentation.

How to Fix:

  • Review and adhere to the API documentation to ensure the correct HTTP methods are used for different API endpoints. Implement checks in the development process to validate request methods.

Server-Side Issues


  • During a major shopping event, an e-commerce site's mobile app experiences 500 Internal Server Errors while interacting with the Shopify API. The server overload during the sale leads to disruptions in API responses.


  • Server-side issues, indicated by 5xx status codes, are beyond the API consumer's control. In this scenario with the Shopify API, server overload during peak shopping times can result in temporary disruptions and internal server errors.

How to Navigate:

  • Adapting to such challenges involves prioritizing critical operations during server overload, implementing retry mechanisms for automatic reattempts, and leveraging caching to store responses locally. These strategies ensure a smoother experience for users, even during high-traffic events like major sales on e-commerce platforms.

Best Practices for Avoiding Failed API Requests

Navigating the intricate landscape of API interactions demands a strategic approach to ensure efficiency and reliability. Let's explore key best practices that empower developers to streamline their API interactions seamlessly:

Robust Error Handling Mechanisms

  • Key Insight: Develop sophisticated error-handling frameworks. Categorize errors intelligently and automate retries for common issues like rate limiting, ensuring a more resilient system.

Comprehensive Monitoring and Analysis

  • Key Insight: Leverage advanced monitoring tools offering real-time analytics, performance tracking, and anomaly detection. Proactively address potential issues before they escalate, keeping your API interactions smooth and efficient.

Mastering API Documentation

  • Key Insight: Dive into documentation for a deep understanding of error codes, rate limits, and request formats. Gain insights from specific examples, like effectively handling a 429 Too Many Requests error, ensuring a smoother development process.

Optimizing API Performance and Scalability

  • Key Insight: Adopt best practices such as load balancing, efficient data caching, and design for scalability from the outset. Regularly test your API's performance under varying loads to ensure it can handle expected traffic peaks, maintaining optimal efficiency.

Secure and Efficient Authentication Management

  • Key Insight: Safeguard API keys with encryption and secure storage. Implement regular key rotation for enhanced security. Monitor and respond to unusual access patterns, ensuring secure and authorized API interactions.

Ensuring API Request Integrity

  • Key Insight: Validate endpoints and payload structures to guarantee data integrity. Regularly test API endpoints under different scenarios to ensure reliability and prevent client-side mistakes.

Adopting a 'Fail Fast' Approach

  • Key Insight: Swiftly identify and abort failing requests. For instance, stop processing after an authentication failure.

This guide provides foundational insights without overwhelming you. Start with these practices and progressively explore more advanced strategies as you become more comfortable with API integration

Leveraging for Optimal API Management

In the dynamic landscape of API interactions, emerges as a game-changer, providing a comprehensive solution to transform challenges into streamlined processes. Let's explore how’s innovative API consumption management platform can enhance your API management experience:

Granular Analytics and Insights:

  • Obtain a detailed view of API performance metrics, such as response times, error rates, and usage patterns, enabling informed decision-making and optimization strategies.

Automated Error Handling and Rate Limit Management:

  • Utilize’s intelligent features to automatically handle common API errors and efficiently manage rate limits, reducing manual overhead and improving reliability.

Proactive Monitoring and Alerts:

  • Stay ahead of potential issues with's state-of-the-art monitoring systems, providing real-time alerts and detailed analytics for proactive issue resolution.

Conclusion: Managing your Egress API Traffic 

Navigating the world of API requests and responses is a critical skill in modern software development. By understanding common pitfalls, implementing strategic best practices, and leveraging advanced platforms like lunar, developers and organizations can ensure seamless, efficient, and robust API interactions. 

For a deeper dive into maximizing API management efficiency, explore our comprehensive article on The Case for a Third-Party API Management Platform. If you're ready to enhance your API management further, discover how’s Egress Proxy can elevate your API interactions and simplify error handling.

Ready to Start your journey?

Manage a single service and unlock API management at scale