What are some common HTTP status code errors and how do you debug them in REST API testing?

Typically a 404 status code is returned if a resource does not exist. However, some applications might return a 404 status code instead of a 401 status code to protect against potential attacks by not divulging that the resource in question exists and requires authentication.

Common HTTP status code errors in REST API testing include: 400 Bad Request: Indicates that the request sent by the client is invalid. 401 Unauthorized: Shows that the client needs to authenticate to gain access. 404 Not Found: Indicates that the requested resource could not be found on the server. 500 Internal Server Error: Suggests that there's an issue on the server side. To debug these errors: Check the request payload for any mistakes. Verify authentication credentials for 401 errors. Ensure that the requested resource exists for 404 errors. Review server logs and code for 500 errors.

In our Salesforce Api, we are commonly facing 401:- Authorization Error, this means you are not authorised for the API or if you are using OAuth 2.0 then your token must be expired 204:- No Content, this means your API Parameters are wrong which returns nothing to the request 500:- Internal Server Error, this means your server must have some problems or your server is down 503:- Service Unavailable, which Means too many requests are sent and now the server is unable to accept more requests There are a total of 9-10 Error codes which you can face in API testing but these 4 mentioned above will face frequently

The HTTP status codes 404 (Not Found), 400 (Bad Request), 500 (Internal Server Error), and 401 (Unauthorised) are a few of the often occurring faults. These errors show a number of problems, including failed authentication, server-side errors, invalid requests, and resources not found.

400 Bad Request: Meaning: The server couldn't understand the request due to invalid syntax, missing parameters, or incorrect formatting. Debugging: Check for typos or syntax errors in the request URL or headers. Ensure all required parameters are present and in the correct format. Verify that the request body is properly formatted (e.g., JSON, XML). Consult API documentation for specific formatting guidelines.

When debugging 5xx error codes in REST API testing, it’s essential to understand the significance of these status codes and how to troubleshoot them effectively. Let’s dive into the world of HTTP status codes and explore best practices for handling server errors: HTTP Status Codes Overview: HTTP status codes are three-digit codes returned by a server in response to an HTTP request. They indicate the outcome of the request and provide information about the result of the operation. These codes are part of the standard that governs communication between client and server over the web. There are five classes of HTTP status codes: 1xx (Informational): Indicates that the request is being processed.

Debugging 5xx error codes in REST API testing involves a step-by-step process to identify and resolve the issue. Firstly, check if the error code is consistent and reproducible, ensuring it is not a temporary issue. Next, examine the error message or response body provided by the server to understand the specific error details. Review the server logs to gain more insights into the error, investigating for any server-side issues like database connection problems or gateway timeouts. By systematically analysing the error, its source, and collaborating with the necessary stakeholders, the root cause can be identified, and appropriate troubleshooting steps can be taken to rectify the 5xx error code in the REST API.

401 Unauthorized: Meaning: The request requires authentication, but the credentials provided are invalid or insufficient. Debugging: Double-check the accuracy of your authentication credentials (username, password, token). Ensure you're using the correct authentication method (e.g., basic, bearer). Verify that the credentials have the necessary permissions for the requested resource.

5xx Server Errors: These errors occur when the server encounters an unexpected condition that prevents it from fulfilling the request. Examples include: 500 Internal Server Error: Indicates a generic server-side error occurred, often due to misconfiguration, code bugs, or resource exhaustion. 503 Service Unavailable: Indicates that the server is temporarily unable to handle the request due to overload or maintenance. Debugging Technique: When encountering 5xx server errors, investigate the server-side logs, error messages, and stack traces to identify the underlying issue. Look for clues such as database connection failures, runtime exceptions, or memory leaks.

Basically API error codes in 5xx series are to represent that there is an issue from server side. 500 Internal server error & 503 Service unavailable are commonly seen error codes in 5xx series.

When verifying HTTP status codes, it’s essential to examine both the response body and the headers. Let’s break it down: HTTP Status Codes: These codes indicate whether a specific HTTP request has been successfully completed. They are grouped into five classes: Informational responses (100 – 199): These provide interim information about the request. Successful responses (200 – 299): These indicate that the request succeeded. Redirection messages (300 – 399): These inform the client about further actions needed to fulfill the request. Client error responses (400 – 499): These indicate issues with the client’s request. Server error responses (500 – 599): These indicate problems on the server side.

Ensure that the returned response matches your expectations. Check the HTTP status code to confirm it is a 2xx code, such as 200 (OK) or 201 (Created). Additionally, review the response payload for any relevant data. If you encounter unexpected behavior or missing data, verify the request parameters you sent to the API. Double-check that all required parameters are included and correctly formatted. It may be helpful to log the exact request you sent to compare it against the expected behaviour. if you are unable to resolve the issue by yourself, consider reaching out to the API provider's support or consulting their community forums for assistance.

403 Forbidden: Meaning: The server understood the request, but refuses to fulfill it due to lack of authorization. Debugging: Ensure your credentials have the required permissions for the resource. Check if any access control restrictions are in place. Consult with API administrators if necessary.

2xx Success Codes: These codes indicate that the server successfully processed the request and returned the desired outcome. Examples include: 200 OK: Indicates that the request was successful, and the server returned the requested resource. 201 Created: Indicates that the request resulted in the creation of a new resource on the server. Debugging Technique: While 2xx codes signify successful responses, it's essential to verify that the server's response aligns with the expected behavior defined in the API documentation. Perform assertions and validation checks on the response payload, status codes, and headers to ensure correctness and completeness.

API response code 2xx series are all success codes represents that request made is completed successfully. 200 OK means that request is completed by the server. 201 Created means that request is completed with new resource created on the server. 204 No Content means that request is completed in server but there is no data to be returned. Example deletion of a resource in server can return this response.

HTTP status codes are special elements that determine the server response and are presented as 3-rigid coherent symbols. Each HyperText Transfer Protocol code is used for REST API errors. It’s necessary to understand each HTTP status code to identify problems and solve them. 3xx redirection: this class of HTTP status codes indicates that some special-purpose actions are required to complete the request. For example, 301 = redirection. 4xx client error: this category of response status codes flags that the request cannot be carried out. Additionally, it might mean that there is bad syntax in the request. 400 = bad request. 5xx server error: this class of HTTP status codes is about an unsuccessful server respond.

404 Not Found: Meaning: The requested resource could not be found on the server. Debugging: Verify the URL path and resource identifier (ID) are correct. Check for typos or errors in the URL. Confirm the resource exists on the server.

3xx Redirection Codes: These codes indicate that further action is required to complete the request, typically involving redirection to a different URL. Examples include: 301 Moved Permanently: Indicates that the requested resource has been permanently moved to a new URL. 302 Found: Indicates that the requested resource temporarily resides at a different URL. Debugging Technique: When encountering 3xx redirection codes, follow the redirection flow as specified by the server. Verify that the client correctly handles the redirection and navigates to the new URL. Use network monitoring tools to trace the request-response flow and ensure proper redirection behavior.

3xx Redirection Codes: Common redirection codes include: 301 Moved Permanently: The requested resource has been permanently moved to a new URL. 302 Found: The requested resource has been temporarily moved to a different URL. 303 See Other: The response to the request can be found at a different URL.

Many times at work, I faced HTTP status code errors in REST API testing, highlighting the need for effective testing tools. In my experience, tools like Postman and Fiddler are crucial for executing requests. One thing I’ve found helpful is using logging for a systematic record of actions and errors. Debugging, based on logged information, is key to identifying and resolving issues. Monitoring keeps an eye on API performance while mocking helps simulate scenarios for thorough testing. These tools and techniques are vital for troubleshooting HTTP status code errors and helping the testing process in .NET Core development or any other frameworks.

Effective REST API testing often involves utilizing tools such as Postman, cURL, or dedicated testing frameworks. These tools allow for detailed inspection of request and response payloads, headers, and status codes. Automated testing, especially with frameworks like Selenium or tools like Newman for Postman, can streamline the process and facilitate continuous integration and deployment.

Whenever two systems (services) are interact with each other, One more thing is crucial to maintain the contract which is API Contract Testing This helps Verify that the API adheres to the defined contract. This ensures that any changes to the API do not break existing functionality for consumers, leading to more reliable systems. Automated contract tests can be run frequently to catch regressions introduced by changes to the API. It enhances Collaboration. PACT is the tool which we used to implement contract testing

Testing Tools and Techniques: Automated API testing frameworks (e.g., Postman, REST Assured) for functional testing and validation. Load testing tools (e.g., Apache JMeter, Gatling) for assessing API performance and scalability under various load conditions. API mocking tools (e.g., WireMock, MockServer) for simulating backend responses and testing API integrations in isolation.

Postman, SoapUI, and curl are popular tools for API testing. They provide user-friendly interfaces and features for sending requests, inspecting responses, and validating API behavior. These tools streamline debugging and troubleshooting of HTTP status code errors encountered during REST API testing.

We often miss to notice the response time of the API (specially in the sync APIs). Anything abnormal response time at functional testing should be brought up so that while doing performance testing that doesn't become bottle neck. Just keep an eye on response time everytime you hit the API via postman or other tools

Adhering to best practices is crucial for successful REST API testing and debugging. This includes thorough documentation review, clear communication between development and testing teams, and the use of version control for API specifications. Additionally, implementing proper error handling on both the client and server sides can enhance the debugging process by providing more informative error messages.

Software Testers need to be well-versed in the HTTP status codes to know when APIs should return any of them. APIs should not return a 200 where they should return a 4xx, because 'this is how we do it'.

Along with these, Keep our API tests under version control to track changes and facilitate collaboration. Proper error and exception handling is also required. One more thing to check is that the API fails gracefully and provides helpful messages when encountering errors. Because whenever there is meaningful error message, the user can easily understand it and quickly correct based on the error shown

Validate request parameters and headers meticulously. Leverage automation tools (e.g., Postman, REST Assured) for detailed response analysis. Implement robust error-handling mechanisms in scripts. Document and maintain a reference for common HTTP status codes. Utilize automation frameworks (e.g., Selenium, Cypress) for comprehensive API testing.

Error handling is often overlooked in API Testing. We all need shiny 2xx codes and if we get something else we aren't that interested. But the error codes has too much to say about the API functionalities, performance and security. API Testers should have a detailed knowledge about the error codes if there's something not right, they should ask the developers to configure it correctly. System shouldn't throw a Generic message or error code for all scenarios. For example: When the user name/password is incorrect it should show as "401 Unauthorized" and not as "400 Bad Request".

In addition to the status codes under normal or erroneous circumstances, it is also important to carry out load testing for the APIs. Making sure that response codes are still as expected under load will help in increasing the confidence in the system. It can also help establish limits of how much stress or load a system can take.

In my view, an API specification should clearly outline how to use the API and specify all possible HTTP status codes that the API might return. For example, REST APIs typically return: 2XX: Success 3XX: Redirection 4XX: Client error 5XX: Server error