Understanding 4xx Errors: Common Causes and How to Fix Them

If you’ve ever encountered a “404 Not Found” or “403 Forbidden” message while browsing the web, you’ve experienced a 4xx error. These errors are part of a group of HTTP status codes that signal problems with the client’s request—whether it’s an incorrect URL, missing resource, or unauthorized access attempt. While 4xx errors are common, they can disrupt user experience, hurt SEO performance, and create frustration for site visitors and owners.

In this guide, we’ll explore what 4xx errors are, the different types you may encounter, and the most common causes behind them. More importantly, we’ll provide practical solutions to fix these errors for WordPress and ensure your website runs smoothly. Whether you’re a web developer, site administrator, or someone trying to understand these error codes, this post will help you navigate the ins and outs of 4xx errors and how to address them effectively. Let’s dive in!

What Are 4xx Errors?

4xx errors are a category of HTTP status codes that indicate a problem with the request made by the client (usually the browser or app). These errors suggest the request is malformed or unauthorized or the requested resource is unavailable. Unlike 5xx errors, which signal server-side issues, 4xx errors are typically caused by the client’s actions or inputs.

Common 4xx errors include the 404 Not Found error, which occurs when a user tries to access a page that doesn’t exist, and the 403 Forbidden error, which happens when the server understands the request but refuses to authorize it. Other examples include 401 Unauthorized (when credentials are missing or incorrect) and 400 Bad Request (when the server cannot process the malformed request).

Webmasters and developers must monitor these errors, as they can impact user experience, site performance, and SEO rankings. Resolving 4xx errors often involves fixing broken links, correcting permissions, or providing the appropriate redirects. Understanding and managing 4xx errors is crucial for maintaining a smooth, user-friendly website.

Common 4xx Errors and What They Mean and Tips to Fix Them

What is a 404 Not Found Error?

A 404 Not Found error is one of the most common HTTP status codes and occurs when a user tries to access a web page or resource that the server cannot locate. This error simply means that the server couldn’t find the requested URL, usually because the page has been deleted or moved or the URL was typed incorrectly.

The 404 error is often accompanied by a message such as “Page Not Found” or “The requested URL was not found on this server.” It’s a client-side error, meaning the issue typically stems from something the user did (e.g., clicking a broken link or entering an incorrect URL) or changes made by the website owner (e.g., removing or renaming a page without updating links).

Common Causes of a 404 Not Found Error:

• Incorrect URL: A simple typo or misspelling in the web address can lead to a 404 error.
• Broken or outdated links: Links to pages or resources that no longer exist or have been moved without proper redirects.
• Page removed or moved: If the page was deleted, renamed, or relocated but links weren’t updated, users will encounter a 404 error.
• Faulty redirects: Incorrectly configured redirects (e.g., 301 redirects) can also cause users to land on pages that don’t exist.
• DNS issues: Problems with the domain name system (DNS) may result in a 404 if the server is unreachable or misconfigured.

Tips for Fixing a 404 Not Found Error:

1. Double-check the URL: Ensure the URL you entered is correct. Look for mistakes like missing slashes, extra characters, or incorrect domain names. A simple typo can lead to a 404.
2. Check for Broken Links: If you own the website and users encounter 404 errors from internal links, use a link checker tool to scan your site for broken links. Tools like Google Search Console or third-party services like Screaming Frog can help identify and fix broken links.
3. Implement Redirects: If a page has been moved or deleted, set up 301 redirects to point the old URL to a new, relevant page. This ensures that users and search engines are redirected to the correct location, preventing 404 errors.
4. Update Sitemap and Internal Links: After moving or deleting a page, update your website’s XML sitemap and internal links. This helps search engines and users avoid 404 errors when navigating your site.
5. Create a Custom 404 Page: While you can’t prevent every 404 error, you can make the user experience less frustrating. A custom 404 page with helpful links (e.g., a search bar, popular pages, or a link to the homepage) can guide users to relevant content instead of leaving them stuck on an error page.
6. Check Server Configuration: Website administrators or developers should ensure the server is properly configured to serve the correct content. Incorrect .htaccess settings or faulty server configurations can lead to 404 errors.
7. Clear Browser Cache: Sometimes, cached data may cause a 404 error, especially if you’ve recently made changes to the site (e.g., page renaming or redirects). Clear your browser’s cache and cookies to ensure you’re loading the latest version of the page.
8. Monitor Your Site Regularly: Use tools like Google Analytics and Google Search Console to monitor traffic and identify 404 errors. Addressing these errors promptly will improve user experience and help with SEO.

A 404 Not Found error signals that a page or resource cannot be located, but it can be easily fixed with the right steps. By checking for broken links, ensuring proper redirects, and keeping your site updated, you can minimize 404 errors and improve user experience and search engine rankings. Whether you’re a site visitor or website owner, understanding and addressing 404 errors is crucial to maintaining a smooth, accessible website.

What is a 403 Forbidden Error?

A 403 Forbidden error is an HTTP status code indicating that the server understands the client’s request but refuses to authorize it. Unlike a 401 Unauthorized error, typically when authentication credentials are missing or incorrect, a 403 error implies that the server has received and authenticated the request. Still, access is denied due to insufficient permissions or restrictions set on the server.

In other words, a 403 error means that the client is not allowed to access the requested resource, regardless of whether or not they are logged in or provided the correct credentials. The error message often appears as “403 Forbidden” or “You don’t have permission to access [resource] on this server.”

Common Causes of a 403 Forbidden Error:

• Incorrect file or directory permissions: The server may have restricted access to certain files or directories, preventing the client from viewing them.
• IP-based restrictions: The server might block specific IP addresses or geographic locations, preventing access.
• Misconfigured .htaccess file: An incorrect .htaccess file on Apache servers can restrict access and cause a 403 error.
• Access control lists (ACLs): Servers may only allow certain users, groups, or IPs to access specific resources, denying others.
• Restricted user roles: You might encounter this error when accessing restricted areas if you’re logged in but don’t have the necessary permissions (e.g., as a regular user vs. an admin).
• Security plugins or firewalls: Security measures like plugins, firewalls, or bots protection systems (e.g., Cloudflare, mod_security) can block access to resources they perceive as threats.

Tips for Fixing a 403 Forbidden Error:

1. Check File Permissions: If you’re the site administrator, ensure the file or directory you’re trying to access has the correct permissions. For example, on Linux-based servers, the directory permissions should generally be 755 for directories and 644 for files. Incorrect settings may prevent proper access.
2. Review .htaccess File: If using Apache, check your .htaccess file for incorrect rules blocking access to certain files or pages. For example, deny or allow rules related to IP addresses or user agents might be misconfigured. Backup and then edit the file carefully to remove or correct restrictive rules.
3. Verify User Permissions: If you are logged in but encountering a 403 error on certain pages, make sure your user account has the appropriate permissions to access the content. Administrators can verify and adjust user roles and capabilities in the site’s settings.
4. Check IP Restrictions: Some websites limit access by using IP filtering or geolocation-based restrictions. Contact the website’s administrator to request access if necessary.
5. Clear Browser Cache and Cookies: Sometimes, outdated or corrupted cookies and cached data can lead to a 403 error, especially if logged into the site. Clear your browser’s cache and cookies, and try accessing the page again.
6. Disable Security Plugins or Firewalls: If you’re the site owner and using security plugins (e.g., Wordfence, Sucuri) or firewalls (e.g., Cloudflare, mod_security), check their settings for any restrictions that might be blocking access. Temporarily disabling or adjusting these security settings can help pinpoint the cause of the 403 error.
7. Check for HTTP Referer Issues: Some websites or applications are configured to only allow access to certain resources from specific pages or URLs (via the “Referer” header). If you’re trying to access a resource directly (e.g., via a bookmark or external link), ensure it’s allowed by the website’s security settings.
8. Contact the Website Administrator: If you are a user trying to access a website and encounter a 403 error, it’s possible that the issue lies with the website’s settings rather than your browser or device. In this case, the best action is to contact the website’s administrator or support team.

A 403 Forbidden error signals that the server actively denies access to the requested resource, often due to incorrect permissions, restrictions, or security settings. Fixing a 403 error generally involves checking file and directory permissions, reviewing server configurations like .htaccess files, and ensuring that user access controls are properly set. Whether you’re a website visitor or owner, understanding the cause of a 403 error is key to resolving the issue and regaining access to restricted content.

What is a 402 Payment Required Error?

The 402 Payment Required error is an HTTP status code that indicates the request cannot be processed because the client needs to make a payment or provide a valid payment method before proceeding. This error is part of the 4xx class of status codes used to signal client-side issues, but the 402 Payment Required status is not commonly encountered on most websites.

Originally, the 402 Payment Required code was intended for digital payment systems (such as microtransactions or subscription-based content). However, it is rarely used in practice, and its specific use case has not been widely adopted in HTTP standards. In some instances, this error is used by websites or services that require a payment or subscription to access specific features or content, such as premium memberships or paid API usage.

The error is typically seen when accessing a paid service or resource without meeting the payment requirements or when an account’s payment information is incomplete, expired, or invalid.

Common Causes of a 402 Payment Required Error:

• Unpaid Subscription or Service: The user may be attempting to access a premium service or subscription-based content that requires payment, and their subscription has expired or hasn’t been paid.
• API or Paid Features: Access to certain APIs or premium features might be restricted until payment. If a user hasn’t paid for the service, the server will return a 402 error.
• Expired Payment Information: If your credit card or payment method has expired or declined, you might see this error when accessing paid resources.
• Incomplete Checkout or Payment Process: If a user has started a payment process but has not completed it, they may receive a 402 error when accessing the requested content.
• Blocked or Restricted Account: Some websites or services may block access to users who violate payment terms, such as not paying on time or exceeding a service’s usage limits.

Tips for Fixing a 402 Payment Required Error:

1. Verify Your Subscription or Payment Status: If you’re trying to access a paid service, check whether your subscription is active and up to date. If you’ve missed a payment or your account is overdue, try updating your payment method or making the required payment to restore access.
2. Check Payment Method: Ensure your payment details (credit card, PayPal, etc.) are current and valid. An expired or declined payment method is a common reason for encountering this error. Update your payment information and try again.
3. Complete the Payment Process: If you were in the middle of a payment transaction or subscription process and didn’t complete it, return to the payment page and finish the checkout. This might resolve the issue if the system hasn’t recorded your payment.
4. Review Service Terms: Some services have usage limits or restrictions that require additional payments once a certain threshold is reached. For example, an API might have a free tier but restrict usage or access once you exceed a set number of requests. Ensure that you’ve not exceeded the free tier or the agreed-upon usage limits.
5. Contact Customer Support: If you’ve verified that your payment information is correct and you’re still encountering the error, contact the service’s customer support team. They can help you determine why your access is blocked and guide you through resolving any issues related to payment or account restrictions.
6. Check for Platform-Specific Issues: Some platforms or services use a 402 error for custom reasons related to payment or billing, so the context of the error may vary. Look for any announcements or documentation specific to the website or service you’re using to see if there are known issues affecting payments or access.
7. Ensure Compliance with Payment Systems: For website owners or developers, if you’re building a service that uses 402 as part of its business model (e.g., subscriptions, paywalls, or API access), make sure your payment system is configured correctly. Double-check your payment processing system, API billing, and subscription handling to ensure the 402 code is triggered accurately when payment is required.

The 402 Payment Required error signals that a payment is needed to access a service, page, or resource. While it is not commonly seen in everyday web browsing, it may appear on websites offering subscription-based services or paid content. Fixing a 402 error typically involves resolving payment or subscription issues, such as updating payment methods, completing transactions, or ensuring that account terms are met. Whether you are a user trying to access a paid service or a website owner managing access to paid content, understanding the 402 Payment Required error can help you resolve the issue and continue accessing or offering services.

What is a 401 Unauthorized Error?

A 401 Unauthorized error is an HTTP status code that occurs when a client (such as a web browser or an API request) attempts to access a resource or page that requires authentication but fails to provide valid credentials. This error indicates that the server has received the request but cannot authorize the client to access the requested resource due to missing or incorrect authentication details.

In simpler terms, the 401 error means “you need to log in or provide proper credentials to access this content.” It’s often encountered when trying to access a password-protected area of a website, an API endpoint that requires a key, or any resource with restricted access.

Common Causes of a 401 Unauthorized Error:

• Missing or incorrect credentials: The client may not have provided any authentication information, or the information (such as a username/password or API key) is incorrect.
• Expired or invalid session: The request may be denied if the authentication token or session is expired.
• Improper authentication method: The server might expect a specific type of authentication (e.g., Basic Auth, OAuth) that the client doesn’t provide or support.
• Insufficient permissions: The authenticated user may not have access to the resource.
• IP or geographic restrictions: Some servers restrict access based on the client’s IP address or geographic location, resulting in a 401 error for unauthorized attempts.

Tips for Fixing a 401 Unauthorized Error:

1. Check Your Login Credentials: Enter the correct username and password to access a protected page or service. Double-check for typos or case-sensitive entries.
2. Log Out and Log Back In: Session cookies or tokens can sometimes become invalid. Logging out of the site and logging back in can often resolve the error, especially if your session has expired.
3. Clear Browser Cache and Cookies: Corrupted or outdated authentication cookies may cause issues. Try clearing your browser’s cache and cookies, then attempt to access the resource again.
4. Verify Authentication Method: Ensure that the authentication method you’re using (e.g., Basic Auth, OAuth, API keys) is the correct one for the server. If using an API, ensure your headers or tokens are properly configured.
5. Check Permissions: If you’re a website administrator or developer, ensure that the user account attempting to access the resource has the correct permissions. Sometimes, users may be authenticated but lack the required permissions for the requested resource.
6. Review Server Configuration: Developers or administrators should check the server’s configuration files to ensure that authentication settings (e.g., .htaccess, .htpasswd, API token settings) match the access control policies.
7. API Key or Token Validation: If you’re using an API, ensure the API key or token hasn’t expired. Check that the key or token is correctly included in your request headers and has the necessary permissions for the operation you’re trying to perform.
8. Contact the Website or Server Admin: If you’re still receiving a 401 error and are sure your credentials are correct, there may be an issue with the server’s authentication system. In such cases, contacting the website or server administrator for support may be necessary.

By following these steps, you can identify and resolve the underlying causes of a 401 Unauthorized error, allowing you to restore access to protected resources or pages. Whether you’re a user, developer, or administrator, ensuring proper authentication is key to fixing this issue.

What is a 400 Bad Request Error?

A 400 Bad Request error is an HTTP status code that indicates the server cannot process the request due to malformed syntax or invalid data sent by the client. The server cannot understand the request because it’s incorrect or corrupted somehow. This error often occurs when the client (such as a web browser or app) sends a request that doesn’t conform to the expected structure.

Some common causes of a 400 error include:

• Incorrect URL: Typos, extra spaces, or special characters in the URL.
• Malformed HTTP headers: Improperly formatted or missing headers in the request.
• Corrupted cookies: Issues with cookies or stored data in the browser.
• Large request size: Sending data that exceeds server limits, such as oversized form submissions or file uploads.
• Invalid query parameters: Errors in the parameters used for dynamic URLs or API calls.

Tips for Fixing a 400 Bad Request Error:

1. Check the URL: Make sure the URL is correctly typed with no spaces or special characters. Even a small typo can lead to a 400 error.
2. Clear Browser Cache and Cookies: Corrupted cookies or cached data can sometimes cause a bad request error. Try clearing your browser’s cache and cookies and reloading the page.
3. Examine HTTP Headers: If you’re a developer, check the headers sent with the request. Ensure they are properly formatted and include the necessary information, such as correct content types or authentication tokens.
4. Reduce Request Size: If you’re sending large data, such as uploading a file or submitting a form, ensure the request is within the size limits set by the server. Reducing the amount of data can resolve this error.
5. Check Query Parameters: If the request contains query parameters (e.g., in a URL), verify they are correctly formatted and valid. Incorrect parameters can cause the server to fail to process the request.
6. Test with a Different Browser: Sometimes, browser-specific issues can lead to a 400 error. Testing the site in a different browser or using an incognito/private browsing window can help determine if this is the issue.

By following these steps, you can identify the root cause of the 400 Bad Request error and resolve it, ensuring that both users and search engines can properly interact with your site.

Summary

In summary, 4XX errors are client-side issues that arise when a web server cannot process a request due to problems with the request itself, such as incorrect URLs, missing authentication, or insufficient permissions. These errors, including 400 Bad Request, 401 Unauthorized, 403 Forbidden, and 404 Not Found, can disrupt user experience and even harm SEO if not addressed promptly.

The good news is that most 4XX errors can be fixed with some troubleshooting. Whether correcting a typo in the URL, checking your login credentials, updating user permissions, or setting up proper redirects, resolving these errors ensures a smoother browsing experience for your visitors and helps maintain a well-functioning website. For website administrators, it’s essential to monitor your site regularly for broken links, expired sessions, and misconfigured permissions to keep your site running smoothly.

Understanding the common causes of 4XX errors and applying the right solutions can minimize their impact on your site, improve user satisfaction, and enhance overall website performance. By taking a proactive approach to error management, your website will run efficiently and offer an optimized experience for your users.

However, if you need assistance fixing 4xx issues, let us know for more information about one-time fixes, WordPress maintenance plans, or custom plans.