What is HTTP 417 Status Code (Expectation Failed Response)?

The world of web development and HTTP status codes can be overwhelming for newcomers. With so many different codes to keep track of, it’s easy to get lost in the technical jargon. 

One code that you may come across is the HTTP 417 Status Code, also known as the “Expectation Failed” response. This error can be frustrating and confusing to users. But what exactly does this status code mean?

In this blog post, we will dive into the details of the 417 Status Code, its meaning, and potential causes for encountering this error.

What does the HTTP 417 Status Code mean?

The HTTP 417 Status Code is classified as a client error response code, indicating a specific issue with the request sent to the server. It signifies that the server could not fulfil the expectation stated in the request’s Expect header. 

Essentially, this response is issued when the server is unable to meet the requirements laid out in the Expect header of the request. 

This inability to comply results in a 417 Expectation Failed response, marking a unique situation where the server directly communicates its incapacity to accommodate the client’s expectations. 

Source: RFC7231 Section 6.5.14

HTTP 417 Status Code References

Rails HTTP Status Symbol :expectation_failed

Go HTTP Status Constant http.StatusExpectationFailed

Symfony HTTP Status Constant Response::HTTP_EXPECTATION_FAILED

Python2 HTTP Status Constant httplib.EXPECTATION_FAILED

Python3+ HTTP Status Constant http.client.EXPECTATION_FAILED

Python3.5+ HTTP Status Constant http.HTTPStatus.EXPECTATION_FAILED

When is an HTTP 417 status code used?

The Status Code 417 is utilized when a client’s request includes specific conditions for proactive negotiation, communicated through the Expect header.

Particularly, this 417 Expectation Failed response is issued if the server or intermediary nodes do not support the expectations set forth by the client. In instances where this error message is encountered, the client has the option to resend the request without the Expect header. 

This status code intricately connects with the HTTP 100 Continue response; servers assess request specifics upon receipt through the Expect 100-continue header. Should the server agree to process the message body, it responds with 100 Continue. 

Conversely, a disagreement with the request conditions may lead to a 401 Unauthorized or 405 Method Not Allowed status instead of the anticipated 417 error.

How to Use 417 HTTP Status Codes for a Website?

Implementing the HTTP 417 Status Code on a website involves acknowledging the server’s incapacity to fulfil the expectations set by the client’s Expect request-header field.

How to Check HTTP 417 Status Code Error?

To check for a 417 HTTP Status Code error, one should utilize the web browser’s network tab and developer tools. This feature allows you to monitor all network requests made by the client, including those for every resource the site uses.

Need Expert Help?

Dealing with HTTP 417 Status Code can be daunting, especially when it affects the functionality of your web services. This is where expert assistance becomes invaluable. Reliqus Consulting specializes in troubleshooting and resolving complex web server issues.

Our team ensures that your server configurations meet all necessary expectations, preventing errors like the HTTP 417 and enhancing your site’s reliability. If you’re encountering frequent HTTP 417 errors and need professional help, consider reaching out to us.

We provide tailored solutions that not only address the root cause of your issues but also optimize your web infrastructure for peak performance.

HTTP 417 Status Code Error example

What does a 417 Expectation Failed response look like? Here’s an example.

A client requests to send a pdf article, and the server responds with HTTP 417 error code.

Request

HTTP/1:1

Host: www.example.com

Content-type: pdf

Content-length: 5000

Expect: 100-continue

Response

HTTP/1:1 417 Expectation Failed

Content-type: Text

Content length: 100

<html>

<head>

<title> Expectations not supported </title>

<head>

<body>

<p> Can’t support your request </p>

<body>

</html>

Status Code 417 Special Considerations

When dealing with the HTTP 417 Status Code and 100 Continue headers, both servers and clients have specific considerations to keep in mind.

Servers

Servers encountering HTTP/1.0 requests with an Expect: 100-continue header are expected to ignore this directive, as it falls outside the protocol’s specifications.

Furthermore, if a server has already received the full message body from a client, it is not required to send a 100 Continue response. 

Clients

On the client side, it’s important to note that upon issuing an Expect: 100-continue header, clients are not required to wait indefinitely for a server’s response.

They may proceed to send the message body if a 417 Expectation Failed response or any acknowledgment has not been promptly received. This approach aids in avoiding unnecessary delays in data transmission, ensuring more efficient communication.

Which HTTP Method is used with 417 HTTP Status Codes?

The HTTP methods used with the 417 HTTP Status Code are GET and POST.

GET HTTP Method: The GET method is designed to request a representation of a specified resource. When utilizing the GET method, the intention is solely to retrieve data, not to modify the state of the resource. This makes it a safe method, ensuring that no unintended effects occur on the server. 

POST HTTP Method: On the other hand, the POST method is used to send data to a specific resource, resulting in a change to the server’s state or other actions based on the data submitted. These changes can be diverse, ranging from updating server data to submitting form content. 

Both GET and POST methods can encounter the 417 HTTP Response Status Code, indicating a 417 Expectation Failed response. This response occurs when the server cannot meet the expectations outlined in the request’s Expect header. This scenario can happen with both methods.

What is the Related HTTP Response Header with 417 HTTP Status Code?

There is only one related HTTP response header associated with the 417 HTTP Status Code, which is the Expect HTTP Header. This header is crucial as it outlines the expectations the client has for the server in processing the request satisfactorily.

If these expectations cannot be met, the server responds with a 417 Status Code, signalling an Expectation Failed response.

How the HTTP 417 Status Code Could Affect SEO?

HTTP 417 status codes may not have a direct impact on SEO. Still, they can indirectly influence SEO performance in significant ways. This indirect influence comes through their effect on user experience and the ability of search engines to crawl and index a website properly.

The 417 Expectation Failed response, while not directly affecting SEO rankings, can lead to issues that negatively impact factors search engines consider when ranking websites.

Here are some specific factors that can be affected by HTTP status codes:

• User Experience (UX): A 417 error can frustrate users, leading to a poor user experience. High bounce rates and low engagement metrics can signal to search engines that a webpage does not provide value, potentially harming its rankings.
• Website Accessibility: If a page frequently returns a 417 error, it may become inaccessible to users and search engines alike. This inaccessibility can prevent pages from being indexed or cause them to be de-indexed if they were previously accessible.
• Indexing Issues: As mentioned, search engines are unlikely to index URLs that return a 417 status code. This can lead to a decrease in the number of pages from your website appearing in search results.
• Site Reputation: Frequent 417 errors can damage a website’s reputation with users and search engines, leading to a decline in trust and, subsequently, search engine rankings.

Will Search Engines Index a URL with a 417 Status Code Error?

Search engines, such as Google, will not index a URL that returns a 417 status code error. When a website issues an HTTP 417 Expectation Failed response, it signals a problem that prevents the server from meeting the HTTP request’s Expect header field requirements.

As a consequence, this 417 error can result in a significant loss of search result rankings for the affected URL.

What is the Browser’s Compatibility with 417 HTTP Status Codes?

The 417 HTTP Status Code is universally compatible with all major browsers. This includes widely used browsers such as Chrome, Edge, Firefox, Internet Explorer, Opera, Safari, and Webview Android.

Regardless of the browser used to make a request, if the server cannot meet the specified expectations set in the request’s Expect header, it will return the 417 Expectation Failed response.

Common Issues with HTTP 417 Status Code (Expectation Failed Response) and How to Fix Them

When encountering an HTTP 417 Status Code, it typically indicates that the server cannot meet the requirements specified in the “Expect” request-header field.

Here are some common issues associated with this status code and ways to resolve them:

1. Misconfigured Expect Header

One common issue leading to an HTTP 417 error is a misconfigured Expect header in the request. The Expect header specifies certain expectations that the client has from the server.

To fix this, ensure that the Expect header is correctly set and matches the server’s capabilities.

2. Server Misconfiguration

Server misconfigurations can also trigger an HTTP 417 error. This could be due to incorrect server settings or limitations that prevent it from fulfilling the client’s expectations.

To address this, review and adjust the server configuration to align with the client’s requirements.

3. Outdated Server Software

Outdated server software may lack the necessary features or updates to handle the expectations set by the client, resulting in an HTTP 417 response.

Updating the server software to the latest version can often resolve this issue and ensure compatibility with client requests.

4. Client-Server Compatibility Issues

Compatibility issues between the client and server can lead to an HTTP 417 error. This may arise from differences in protocol versions, communication methods, or unsupported features.

To resolve this, ensure that both the client and server are using compatible versions and configurations to meet each other’s expectations.

What are the Other Similar Status Codes to 417 HTTP Status Codes?

Similar to the HTTP 417 Status Code, there are other status codes that indicate specific issues related to client requests or server responses. These include:

• 414 URI Too Long HTTP Status Code: This status code is returned when the request-target URI is longer than the server is willing or able to interpret. 
• 415 Unsupported Media Type HTTP Status Code: The 415 code is used when the server refuses to accept the request because the payload format is in an unsupported media type. 
• 416 Range Not Satisfiable HTTP Status Code: This code indicates that the server cannot fulfil the requested range specified by the client in the Range header because it is beyond the scope of the target URI’s data.

For those interested in a deeper dive into HTTP status codes and their implications, walking through our HTTP codes series will provide comprehensive insights into errors and best practices for web development.

This series discusses a wide range of HTTP status codes, detailing their causes, effects, and resolutions, enhancing your understanding of web server communication and troubleshooting.