Software Development

10 Type of APIs Error Status Codes and How to Fix?

10 Type of APIs Error Status Codes and How to Fix

When you first use an API, things don’t always go according to plan. This is especially useful if you are a beginner and want to integrate an API into another system. Many times documentation is missing in terms of error status codes. It’s much easier to predict things going well than things going badly.

Many status codes in HTTP can provide information about what happened when an API was called. There are many status codes that can be used to indicate what is happening in HTTP. They range from 100 to 511 and each has a different meaning. However, only 400 to 511 refer to errors. These useful tables show them.

Let’s take a look at the most common HTTP status codes. These indicate an error on either the client or server.

Client-Side Errors

The 4XXX group status codes are usually caused by client-side errors. However, changes to the API could also lead to them. These are the most common errors, and how to fix them.

1. 404 Not Found

This is the most common error code that you can receive. This indicates that the URL used in your request is not available on the server.

This is a 4XX error. It usually indicates that something is wrong on the client side. However, it can also be a sign of a problem on the server. Sometimes API URLs will change after a new version is released, but they may also change if something happens on the server.

Before you check for API issues, it is best to make sure that your client code isn’t missing any typos.

Also read: 15 Best Face Recognition APIs

2. 401 Unauthorized

This status code indicates that you have not yet authenticated against API. The API doesn’t know you and won’t serve you.

For most APIs, You will need to register and obtain an API key. The API will use this key to identify you in an HTTP header when you send a request.

3. 403 Forbidden

The forbidden status indicates that You don’t have permission for this URL to be requested. You are authenticated and this is what makes you different from the Unauthorized status. However, the role or user you are authenticated for cannot make the request. If you are having authentication issues When you use the wrong API key or try to access features that your subscription doesn’t permit.

4. 400 Bad Request

One of the most common error messages is the bad request status. It means that You made a mistake in your request, If there is no error information in the response body, You must verify the medical records. It is possible that you are missing a query, body, or header in your request. You might also find that your request data is not in the correct format.

5. 429 Too Many Requests

API subscription plans come with limits. The lower the plan, the fewer requests you can make for your API key. Throttling your requests in your client is an option if you send too many requests in a short time. This can indicate that your account has reached a daily, weekly, or monthly limit.

An API may sound like a good fit, but once you realize the limitations, it suddenly doesn’t work in your case. Before integrating an API, make sure you check what is included in your API subscription. Otherwise, you could face problems for weeks or even months.

Server-Side Errors

If the server is not catching errors correctly, the 5XX status code group can lead to a 5XX error. However, an invalid request that should have received a 4XX response can result in a 5XX error. These are the most common errors, and how to fix them.

Also read: How to Change PHP Configuration on a Dedicated Server

6. 500 Internal Server Error

This status could mean anything, but most often it means that the API server crashed. This could be caused by request-related issues. Double-check your docs to ensure you have done everything correctly: query fields and body fields, format, headers, etc.

If this didn’t solve the problem, it could also be related to an API upgrade that introduced buggy code or data that the API loaded from a downstream service. If this is the case, you should contact API support.

7. 502 Bad Gateway

This status indicates that the server you called wasn’t actually the API server but a gateway/proxy. The proxy server attempts to call the API server under your name. The status also indicates that the API server did not respond. This could indicate a network problem or that the API server was unavailable for maintenance.

This is usually temporary and should be resolved by the API provider. However, if it persists, you need to contact support.

8. 503 Service Not Available

This indicates that the service is unavailable. The API couldn’t process any additional API requests because too many were being sent. The problem is solved when clients send fewer requests. However, it could also indicate that the API provider did not have enough resources to support all its customers.

If the error is applicable to your case, you can make your client less susceptible to it by waiting to send additional requests. But if the error keeps showing up, you have to contact the API provider.

9. 504 Gateway Timed Out

This status is similar to the bad gateway status. It tells you that the server you calling is a proxy server for the actual API server. The problem this time is that the API server did not respond promptly.

It could be due to high latency between the API server and proxy. This could also indicate that the API server is taking too long to process your request.

This problem can be solved by checking if the content of your request is related to that timeout. You should reduce the amount of data you request or the time it takes to calculate, you should try and cut it down. Contact support if you feel your request is reasonable but the status does not change.

Also read: Top 10 Bug Tracking Tools and Software

10. 501 Not Implemented

The HTTP method used to request the URL is what causes the status not implemented. To make the request, you can use a different method.

Requests with the wrong method will usually result in a status of 404 not found. An unimplemented status means that the method has not been implemented yet. The API creator can use this status for clients to inform them that this method will become available in the future.

Monitoring HTTP Error Codes

It is tedious to track these errors manually and can lead to an error.

API analytics provides monitoring and notification capabilities. This allows you to keep track of HTTP status code errors and gain deeper insights from error code trends. These tools can either be purchased or built by an in-house team.


While you will undoubtedly see many errors when using APIs there are usually reasonable solutions. There are server-side and client-side error codes, which can sometimes cause each other.

To ensure that you don’t miss anything while integrating, make sure to thoroughly read the documentation. Contact the API provider if things are not working.

Written by
Barrett S

Barrett S is Sr. content manager of The Tech Trend. He is interested in the ways in which tech innovations can and will affect daily life. He loved to read books, magazines and music.

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