The "Failed to set referrer policy" error in WordPress is a common issue, particularly impacting sites utilizing security plugins or specific configurations within .htaccess files. While seemingly technical, this error signals a potential vulnerability in how your website handles referral information, impacting both security and privacy. This guide will delve into the causes of this error, its implications, and, most importantly, provide actionable steps to resolve it, even in relation to popular SEO plugins like Yoast SEO. We’ll explore the underlying concepts, various solutions, and how to verify your implementation.
What is the Referrer Policy?
The Referrer Policy is a security mechanism implemented by web browsers to control how much referrer information is sent with HTTP requests. The referrer, or referring URL, is the address of the previous webpage a user visited before arriving at the current page. This information can be valuable for analytics, logging, and even security purposes. However, it can also pose privacy risks, especially when sensitive data is included in the referrer URL.
Historically, browsers sent the full URL as the referrer by default. This meant that if a user navigated from a secure (HTTPS) page to an insecure (HTTP) page, the full URL, including any credentials, could be transmitted over an insecure connection. The Referrer Policy allows website owners and browser developers to mitigate these risks by specifying which referrer information should be sent in different scenarios.
Several policies are available, each offering a different level of security and functionality. These include:
- no-referrer: Never send the referrer information.
- no-referrer-when-downgrade: Send the referrer only when navigating from a secure (HTTPS) page to another secure (HTTPS) page.
- origin: Send only the origin (scheme, host, and port) of the referrer.
- origin-when-cross-origin: Send the origin when the destination is on the same domain, and no referrer when navigating to a different domain.
- same-origin: Send the referrer only when the origin of the current page and the referrer are the same.
- strict-origin: Send only the origin when the protocol scheme is secure.
- strict-origin-when-cross-origin: Send the origin only when the protocol scheme is secure and the destination is on the same domain. No referrer is sent to other origins.
- unsafe-url: Transmit the full URL as the referrer, regardless of security. (Generally discouraged).
- always: Always send the full URL as the referrer. (Generally discouraged).
Why Does the "Failed to Set Referrer Policy" Error Occur?
The error message "Failed to set referrer policy" typically arises from one of two primary causes:
- Invalid Policy Value: The most common reason is an incorrectly formatted or unsupported value specified for the
Referrer-Policyheader. As the error message itself indicates, the value must be one of the predefined policies listed above. Attempting to use a custom value, likehttp://example.com/comic/(as seen in one of the source documents), will inevitably trigger this error. - Malformed Meta Tag: The error can also occur if the
<meta name="Referrer" content="...">tag is used incorrectly. This tag is deprecated and should not be used. The correct method is to use theReferrer-PolicyHTTP header. Furthermore, the meta tag, if present, must contain only one valid token, as highlighted in forum discussions.
The error is often observed in Chrome, as indicated in the initial source, but can manifest in other browsers as well. It's important to note that the error doesn't necessarily break your website's functionality, but it indicates a misconfiguration that could potentially expose your site to security vulnerabilities.
Resolving the Error: A Step-by-Step Approach
Here's a breakdown of how to address the "Failed to set referrer policy" error in WordPress:
1. Inspect Your .htaccess File:
The .htaccess file is a powerful configuration file for Apache web servers. It's a common place to set HTTP headers, including the Referrer-Policy.
- Access: Use an FTP client or your hosting provider's file manager to access the
.htaccessfile in your WordPress root directory. - Backup: Always create a backup of your
.htaccessfile before making any changes. - Review: Search for lines containing
Header set Referrer-Policy. If you find any, ensure the value is one of the valid policies listed earlier. For example:Header set Referrer-Policy "strict-origin-when-cross-origin" - Correct/Remove: If the value is invalid, correct it. If you don't need to explicitly set the referrer policy, consider removing the line altogether. The browser will then fall back to its default policy.
2. Utilize a WordPress Plugin:
Several WordPress plugins simplify the process of managing HTTP headers, including the Referrer-Policy.
- HTTP Headers: This free plugin is a popular choice. Install and activate it from the WordPress plugin directory.
- Configuration: Navigate to Settings > HTTP Headers in your WordPress dashboard. Open the "Security" section and locate the "Referrer-Policy" setting.
- Enable & Choose Policy: Tick the "On" box to activate the policy and select your preferred option from the dropdown menu. "strict-origin-when-cross-origin" is generally a good choice for enhanced security.
- Save Changes: Click "Save Changes."
3. Check for Conflicting Plugins:
In some cases, other security plugins or caching plugins might be interfering with the Referrer-Policy header.
- Deactivate Plugins: Temporarily deactivate other security or caching plugins one by one to see if the error disappears.
- Identify Conflict: If deactivating a specific plugin resolves the issue, investigate its settings to see if it's overriding the
Referrer-Policy.
4. Remove the Deprecated Meta Tag:
Open your theme's header.php file (usually found in wp-content/themes/[your-theme]/). Search for <meta name="Referrer" content="...">. If you find it, remove this line entirely. The Referrer-Policy HTTP header is the preferred method.
5. Verify Your Implementation:
After making changes, it's crucial to verify that the Referrer-Policy header is being sent correctly.
- Online Tools: Use online tools like Security Headers to scan your website and check the HTTP headers.
- Browser Developer Tools: Open your browser's developer tools (usually by pressing F12). Navigate to the "Network" tab, reload your page, and inspect the response headers for the
Referrer-Policyheader.
Referrer Policy and Yoast SEO
While Yoast SEO doesn't directly control the Referrer-Policy header, it's important to ensure that any SEO-related configurations aren't inadvertently causing conflicts. Yoast SEO primarily focuses on meta tags and sitemaps, and shouldn't directly impact the HTTP header settings. However, if you're using a plugin that integrates with Yoast SEO to manage headers, ensure that the integration isn't introducing any errors. The core issue is rarely Yoast SEO itself, but rather a misconfiguration elsewhere on the site.
Comparing Methods for Setting Referrer Policy
Here's a table summarizing the different methods for setting the Referrer Policy, along with their pros and cons:
| Method | Pros | Cons | Difficulty |
|---|---|---|---|
.htaccess |
Direct control, no plugin needed | Requires server access, potential for errors | Medium |
| WordPress Plugin | Easy to use, user-friendly interface | Relies on plugin functionality, potential for conflicts | Easy |
Theme header.php| Direct control (not recommended) |
Deprecated method, less flexible | Medium |
Potential Conflicts and Considerations
As noted in the source data, conflicts can arise between the Referrer-Policy and other .htaccess directives. Be cautious when modifying the .htaccess file, and always back it up first. Incorrectly configured rewrite rules or other directives could interfere with the Referrer-Policy header. Additionally, some hosting environments might have specific configurations that override your settings.
The Bottom Line
The "Failed to set referrer policy" error in WordPress is a solvable issue. By understanding the underlying concepts, carefully reviewing your configuration files, and utilizing the appropriate tools, you can effectively resolve the error and enhance your website's security and privacy. Remember to prioritize a valid Referrer-Policy value, avoid deprecated meta tags, and thoroughly verify your implementation. A proactive approach to security is essential for maintaining a safe and trustworthy online presence.