Website connection errors present significant challenges to search engine optimization efforts, preventing crawlers from accessing and indexing content properly. When websites cannot be reached by search engine bots or SEO analysis tools, it directly impacts visibility and ranking potential. This article examines various connection-related errors that affect SEO, their underlying causes, and practical solutions to ensure proper site accessibility.
Common Website Connection Errors Impacting SEO
Several HTTP status codes can indicate connection problems that significantly impact a website's SEO performance. These errors prevent search engine crawlers from accessing content, which can lead to indexing issues and reduced visibility in search results.
502 Bad Gateway Errors
A 502 Bad Gateway error occurs when a server acting as a gateway or proxy receives an invalid response from an upstream server. For SEO purposes, this error disrupts the crawling process, preventing search engines from accessing valuable content. The typical steps for addressing a 502 error include refreshing the page, verifying the correct URL was used, clearing the browser cache, performing a DNS flush, and contacting the hosting provider for assistance. These errors can be particularly problematic when they occur frequently, as they may signal to search engines that the site is unreliable, impacting user experience and search performance.
503 Service Unavailable Errors
The 503 Service Unavailable error indicates that the server is currently unable to handle requests due to temporary overload, scheduled maintenance, or the server's connection rejection. This response is meant to be temporary, signaling that the service should be restored after some delay. The SEO impact of 503 errors ranges from moderate to high. While temporary unavailability may not have an immediate negative effect on SEO, persistent problems signal to Google that the site cannot be trusted, potentially harming its ranking. To resolve a 503 error, website administrators can refresh the page, ensure URL accuracy, consider temporarily disabling their CDN, and reach out to their hosting provider for support. When planning maintenance, it's recommended to use the 503 status code and ensure headers specify that the condition is temporary, along with keeping users informed of expected return times.
403 Forbidden Errors
The Blocked Due to Access Forbidden (403) error in Google Search Console is common and can significantly hinder a website's SEO performance by preventing Googlebot from accessing and indexing crucial URLs. Addressing these errors requires careful examination of various potential causes, including server configurations and CMS settings. The solution involves changing settings that block Googlebot while ensuring the approach meets both accessibility needs for search engines and security requirements for the site. It's important to note that 403 errors on pages intentionally kept private are correct and should remain in place. Shared hosting environments and high traffic spikes can also trigger server blocks, requiring consultation with the hosting provider in such cases.
HTTPS/SSL Certificate Issues and SEO Implications
The transition to HTTPS has become a critical factor in website SEO, with security certificate issues potentially causing significant visibility problems.
"This Site Can't Provide a Secure Connection" Errors
This error occurs when a website claims HTTPS compliance but does not provide a correct certificate or uses an incorrect one. When the certificate cannot be verified, browsers refuse to load the site and instead display error messages. The underlying issue is that the website is transmitting data over HTTP rather than HTTPS, which does not encrypt data between the user's browser and the server, exposing users to potential security risks like man-in-the-middle attacks or data eavesdropping.
Browser-Specific Warning Messages
Various browsers display this security warning differently: - Google Chrome shows "this site can't provide a secure connection" - Mozilla Firefox displays "Warning potential security ahead" - Microsoft Edge presents "Can't connect securely to this page"
These warnings do not imply malware infection but rather notify users that they are not connected to the page over a secure connection. Website owners must implement proper security measures to address these issues, as non-compliance with Google's SSL requirements can heavily impact a site's SEO, particularly due to the adverse effects of poorly implemented SSL protocols.
SEO Impact of Non-Secure Websites
The "Not Secure" warning prominently displayed by Google in bright red text can significantly impact user trust and, consequently, SEO performance. This designation appears when websites load via HTTP instead of HTTPS, potentially warning users about security risks. Poorly implemented SSL protocols can create additional issues, and while the warning doesn't affect malware status, it signals potential vulnerabilities in the connection. Website owners must safeguard their sites to maintain both security and search engine rankings, as non-secure connections may deter users and signal quality issues to search engines.
Security Measures Blocking SEO Crawlers
Modern websites implement various security measures that, while necessary for protection, can inadvertently block SEO crawlers and analysis tools.
Firewalls and Security Tools
Firewalls, security tools, and CDNs such as Cloudflare and Incapsula may block SEO analysis servers or cause requests to timeout. When this happens, SEO tools may display errors like "We were unable to parse the content for this site." For example, the All in One SEO tool may encounter this issue if security services prevent their servers from accessing the website. In such cases, adding specific IP addresses as whitelisted addresses may resolve the issue. For All in One SEO, the recommended IP addresses to whitelist are: - 104.236.26.134 - 159.89.243.35
However, some security services may still not allow SEO analysis servers through due to their policies, leaving no solution for the website owner.
CDN Restrictions
Content Delivery Networks (CDNs) can sometimes interfere with SEO crawlers by blocking access or slowing response times. When CDN settings are too restrictive, they may prevent search engine bots from accessing content, leading to crawling issues. A potential workaround for connection issues related to CDNs is to temporarily disable them during troubleshooting to determine if they're causing the problem. If this resolves the issue, the CDN settings can be adjusted to allow proper crawler access while maintaining security benefits.
Robots.txt and Crawl Directives
The robots.txt file can inadvertently block SEO crawlers if not properly configured. When external SEO tools attempt to crawl pages and find them blocked by robots.txt, they cannot index or crawl the content. Additionally, "noindex" meta tags in the HTML head of pages can prevent indexing and crawling. For HubSpot pages specifically, common causes for crawling issues include: - Pages being included in the robots.txt file - "Noindex" meta tags preventing crawling - Auditing a root domain rather than the subdomain connected to HubSpot - Expiring links for RSS feeds and blog listing pages - Non-essential resources prompting blocked resources errors
Whitelisting Requirements for SEO Tools
Different SEO tools and crawlers require specific whitelisting to ensure proper access to website content.
All in One SEO Tool Requirements
The All in One SEO Analysis tool runs from the provider's servers, which must be able to reach the website to scan for common SEO problems. If the website is hosted locally and still in development, it must first be published online before the servers can scan it. When encountering "We were unable to parse the content for this site" errors, users with CDNs, firewalls, or security services should add the specific IP addresses (104.236.26.134 and 159.89.243.35) to their whitelist. If unsure about the implementation, reaching out to the hosting provider to whitelist these IP addresses is recommended.
Semrush Bot Requirements
Semrush's On Page SEO Checker crawler may be blocked or unable to crawl pages, resulting in "page is not accessible" notes. To resolve this, website administrators should check the robots.txt file to ensure it allows Semrush's user agents to crawl pages. If not blocked in robots.txt, the following IP addresses and user-agent should be whitelisted: - IP addresses: 85.208.98.53 and 85.208.98.0/24 - User-agent: SemrushBot-SI - Port options: Port 80 (HTTP) or Port 443 (HTTPS)
Additionally, the Site Audit bot used by Semrush should be whitelisted at IP address 85.208.98.128/25 with the user-agent name "SiteAuditBot". If encountering "SEMRushBot-Desktop couldn't crawl the page because it was blocked by robots.txt," the issue may be that crawl-delay settings in robots.txt don't comply with On Page SEO Checker requirements. The tool's crawlers only accept a crawl-delay of 1 second, and anything above this value would cause the crawler to ignore the page.
HubSpot Crawler Considerations
When external SEO tools like Moz or Semrush attempt to crawl HubSpot pages, several issues may prevent successful crawling. The HubSpot crawler uses the user agent "HubSpot Crawler," which should be added to the allow list as an exemption by site administrators. Other common causes for crawling issues with HubSpot pages include: - Pages included in the robots.txt file - "Noindex" meta tags in the HTML head - Auditing a root domain instead of the HubSpot-connected subdomain - Expiring links for RSS feeds and blog listing pages - Non-essential resources prompting blocked resources errors
Ensuring Search Engine Crawlers Can Access Your Site
Proper accessibility for search engine crawlers is fundamental to SEO success. Several strategies can help verify and maintain this accessibility.
Verifying DNS Resolution
DNS resolution issues can prevent search engine crawlers from accessing websites. To verify that DNS can resolve the URL, website administrators should check their domain name system settings and ensure proper configuration. Google's documentation provides detailed guidance on resolving DNS errors, which should be consulted when troubleshooting connection issues. Proper DNS resolution ensures that search engine bots can successfully locate and access website content.
Checking for Proper Crawl Access
Regularly checking for proper crawl access is essential for maintaining SEO performance. This involves verifying that robots.txt files are not inadvertently blocking important pages, ensuring that noindex directives are only applied to pages that shouldn't be indexed, and confirming that server configurations allow crawler access. For HubSpot users, auditing the correct subdomain rather than the root domain is crucial. Additionally, monitoring for expiring links on RSS feeds and blog listing pages can prevent blocked resources errors that might impact crawling efficiency.
Monitoring Google Search Console
Google Search Console provides valuable insights into how Googlebot interacts with a website, including any crawl errors encountered. Regularly monitoring Search Console for Blocked Due to Access Forbidden (403) errors and other access-related issues allows website administrators to address problems promptly. When such errors appear, it's important to determine whether they affect public-facing pages that should be indexed or private pages that should remain inaccessible. For public pages requiring access, server configurations and CMS settings should be adjusted to allow proper crawling while maintaining necessary security measures.
Conclusion
Website connection issues represent a significant but often overlooked challenge in SEO strategy. The various HTTP errors that can occur—502 Bad Gateway, 503 Service Unavailable, and 403 Forbidden—each present unique obstacles to search engine crawlers, potentially impacting indexing and rankings. Similarly, HTTPS/SSL certificate issues not only affect user trust but can also signal quality problems to search engines.
Security measures implemented to protect websites, including firewalls, CDNs, and robots.txt directives, while necessary for protection, can inadvertently block SEO crawlers and analysis tools. The solution often involves carefully whitelisting specific IP addresses and user agents used by various SEO tools to ensure they can access and analyze website content properly.
For website administrators, maintaining accessibility for both search engine crawlers and SEO analysis tools requires ongoing attention to server configurations, security settings, and crawl directives. By proactively addressing connection issues and ensuring proper whitelisting of legitimate crawlers, businesses can maintain their SEO performance while keeping their websites secure and functional.