The Ultimate Technical SEO Checklist: Errors, Warnings, and Optimization Opportunities

October 30, 2024
Gulrukh Ch
SEO

Technical SEO refers to optimizing a website’s backend aspects to improve its search engine visibility and performance. It focuses on elements such as site structure, indexing, crawling, page speed, and mobile compatibility, which are crucial for search engines to access and rank a website properly. Unlike on-page SEO, which involves content optimization like keywords and meta tags, technical SEO ensures that the website’s infrastructure is sound and efficient. Both are essential for boosting rankings, but technical SEO handles the behind-the-scenes mechanics, ensuring smooth functioning and accessibility. This makes technical SEO a critical part of an overall SEO strategy.

Why Technical SEO is Important

Technical SEO is crucial in enhancing a website’s performance in search results. It’s not just about doing the right things; it’s about doing them efficiently. Improving crawlability and indexing ensures that search engines can efficiently navigate and display your site, making it more likely to appear in search results. Optimizing page speed, mobile-friendliness, and site architecture leads to a better user experience, reducing bounce rates and boosting engagement.

A technically optimized site also has an advantage over competitors, many of whom neglect this aspect. Ultimately, technical SEO builds a strong foundation, supporting the long-term success of both on-page and off-page SEO efforts making your SEO efforts more productive and effective.

Errors

Technical errors can significantly hinder your website’s performance and visibility in search engines. Identifying and fixing these issues is critical to maintaining a healthy site that ranks well and provides a seamless user experience. Below, we break down common technical SEO errors, their causes, and actionable solutions to address them.

5xx Errors

Problem: These server-side errors (e.g., 500, 503) occur when the server is unable to fulfill a request due to a malfunction or overload.
Impact: Users can’t access the website, causing poor user experience and loss of rankings as search engines can’t crawl the affected pages.
Solution: Check server logs for specific causes, increase server capacity, or contact hosting providers for support.

4xx Errors

Problem: Client-side errors (e.g., 404 not found) occur when a user or search engine requests a page that doesn’t exist or can’t be accessed.
Impact: Poor user experience, wasted crawl budget, and potentially lost rankings for linked pages.
Solution: Set up 301 redirects for moved pages or create a custom 404 page to guide users.

Missing Title Tags

Problem: Pages without title tags are missing key metadata used by search engines to understand content.
Impact: Reduced SEO performance and poor click-through rates in search results.
Solution: Ensure all pages have unique and descriptive title tags.

Duplicate Title Tags

Problem: Multiple pages have identical title tags, causing confusion for search engines.
Impact: Difficulty ranking the correct page, leading to potential keyword cannibalization.
Solution: Write unique title tags for each page that reflect its content.

Duplicate Content

Problem: Same or very similar content appears on multiple pages or across different domains.
Impact: Search engines may penalise the site for redundancy, leading to lower rankings.
Solution: Use canonical tags to indicate the preferred version of a page or remove duplicate content.

Broken Internal Links

Problem: Internal links point to non-existent or moved pages.
Impact: Bad user experience, wasted crawl budget, and potential SEO penalties.
Solution: Regularly audit and fix broken internal links.

Pages Not Crawled

Problem: Pages are not accessible to search engine crawlers, possibly due to restrictions in robots.txt or server issues.
Impact: Pages won’t appear in search results, limiting visibility and traffic.
Solution: Check crawl settings in robots.txt and Google Search Console, and resolve server issues.

DNS Resolution Issue

Problem: The domain name system (DNS) is unable to resolve, meaning the browser cannot find the website’s IP address.
Impact: Users can’t access the site, leading to downtime and potential loss of traffic.
Solution: Check DNS settings and work with the hosting provider to resolve any configuration issues.

We Couldn’t Open the Page’s URL

Problem: Search engine crawlers cannot access a specific page.
Impact: Search engines can’t index the page, reducing its visibility.
Solution: Verify that the page is accessible, check for errors like 403 (forbidden) or 404, and ensure proper permissions.

Broken Internal Images

Problem: Images on the website are missing or fail to load due to incorrect file paths or deletion.
Impact: Poor user experience and negative impact on visual content engagement.
Solution: Audit the site for missing images and update file paths or re-upload them as needed.

Duplicate Meta Descriptions

Problem: Multiple pages have identical meta descriptions.
Impact: Search engines struggle to differentiate between pages, potentially reducing click-through rates.
Solution: Write unique, compelling meta descriptions for each page.

Invalid Robots.txt Format

Problem: The robots.txt file is improperly formatted, leading to miscommunication with search engines.
Impact: Crawlers may unintentionally block important pages or resources.
Solution: Validate the robots.txt format using Google Search Console or other tools, and correct any errors.

Invalid Sitemap.xml Format

Problem: The sitemap.xml file contains errors, making it unreadable for search engines.
Impact: Search engines may miss important pages when crawling the site.
Solution: Use sitemap validation tools to identify and correct the errors in the file.

Incorrect Pages Found in Sitemap.xml

Problem: The sitemap contains pages that shouldn’t be indexed (e.g., old or duplicate content).
Impact: Crawlers waste time and resources, reducing the efficiency of indexing important pages.
Solution: Update the sitemap to include only relevant and indexable pages.

www Resolve Issues

Problem: The website is accessible through both www and non-www versions without proper redirects.
Impact: Can lead to duplicate content issues and diluted SEO efforts.
Solution: Set up a 301 redirect from one version to the other to ensure consistency.

Viewport Not Configured

Problem: No viewport meta tag is set, making the site unoptimized for mobile devices.
Impact: Poor mobile user experience and potential SEO penalties from Google.
Solution: Add a viewport tag in the HTML to make the site responsive.

Large HTML Page Size

Problem: Pages have excessively large HTML sizes, slowing down loading times.
Impact: Poor user experience, increased bounce rates, and lower search rankings.
Solution: Optimize the HTML by minifying code and removing unnecessary elements.

Missing Canonical Tags in AMP Pages

Problem: AMP pages are missing canonical tags pointing to the original content.
Impact: Search engines may treat AMP pages as duplicate content.
Solution: Ensure all AMP pages have canonical tags linking to their corresponding original versions.

Issues with Hreflang Values

Problem: Incorrect or missing hreflang values cause problems for international SEO.
Impact: Search engines may serve the wrong language version of your site to users.
Solution: Correct hreflang values to ensure the right language and region version appears for each user.

Hreflang Conflicts Within Page Source Code

Problem: Conflicting hreflang tags within the page’s source code confuse search engines.
Impact: Reduced international ranking and traffic due to improper targeting.
Solution: Fix any conflicts and ensure hreflang values are consistent.

Issues with Incorrect Hreflang Links

Problem: Incorrect hreflang links point to the wrong URLs.
Impact: Search engines may misinterpret regional targeting.
Solution: Audit hreflang links and fix incorrect URL values.

Non-Secure Pages

Problem: Pages are served over HTTP instead of HTTPS.
Impact: SEO penalties from Google, browser security warnings, and user trust issues.
Solution: Migrate all pages to HTTPS.

Certificate Expiration

Problem: SSL certificate has expired.
Impact: Browser warnings, blocked access to the website, and SEO penalties.
Solution: Renew the SSL certificate with your hosting provider.

Old Security Protocol Version

Problem: The site uses outdated security protocols such as SSL or early versions of TLS.
Impact: Vulnerability to attacks, browser warnings, and lower SEO rankings.
Solution: Upgrade to the latest TLS version for better security.

Certificate Registered to Incorrect Name

Problem: The SSL certificate does not match the website domain.
Impact: Browser warnings and potential security risks.
Solution: Obtain an SSL certificate for the correct domain name.

Issues with Mixed Content

Problem: Pages load both secure (HTTPS) and insecure (HTTP) elements.
Impact: Browser security warnings and potential SEO penalties.
Solution: Update all resources (images, scripts) to load over HTTPS.

Neither Canonical URL Nor 301 Redirect From HTTP Homepage

Problem: No canonical URL or 301 redirect is set from the HTTP version of the homepage to the HTTPS version.
Impact: SEO issues and duplicate content risks.
Solution: Set up a 301 redirect from the HTTP homepage to the HTTPS version.

Redirect Chains and Loops

Problem: Multiple redirects in a sequence or an infinite loop.
Impact: Slower load times and wasted crawl budget, leading to poor SEO performance.
Solution: Simplify redirects to a single step, and fix any looping issues.

Broken Canonical URLs

Problem: Canonical tags point to non-existent or incorrect URLs.
Impact: Confuses search engines and can cause indexing issues.
Solution: Fix broken canonical URLs to point to valid pages.

Multiple Canonical URLs

Problem: Multiple canonical URLs are specified for a single page.
Impact: Causes search engines to misinterpret which version is the main one.
Solution: Ensure only one canonical URL is set for each page.

Meta Refresh Redirects

Problem: Pages use meta refresh tags to redirect instead of server-side 301 redirects.
Impact: Confuses search engines and users, leading to potential SEO penalties.
Solution: Use 301 redirects instead of meta refresh tags.

Broken Internal JavaScript and CSS Files

Problem: JavaScript and CSS files are missing or broken.
Impact: Poor page functionality and user experience, potentially hurting rankings.
Solution: Audit and fix broken script or stylesheet paths.

Insecure Encryption Algorithms

Problem: The website uses outdated or weak encryption algorithms.
Impact: Security vulnerabilities, potential SEO penalties, and user trust issues.
Solution: Upgrade to modern encryption algorithms like AES-256.

Too Large Sitemap.xml

Problem: Sitemap.xml file exceeds size limits (50 MB or 50,000 URLs).
Impact: Search engines may not fully crawl or index the sitemap.
Solution: Split the sitemap into smaller files and link them in a sitemap index.

Malformed Links

Problem: Links on the website are incorrectly formatted or broken.
Impact: Negative user experience and lost link equity.
Solution: Regularly check and fix malformed or broken links.

Invalid Structured Data Items

Problem: Structured data on the page is incorrectly formatted or missing required fields.
Impact: Rich search result features may not appear, lowering visibility.
Solution: Validate structured data using Google’s Structured Data Testing Tool and correct any errors.

Viewport Width Not Set

Problem: No viewport width is set, leading to unresponsive design on mobile devices.
Impact: Poor mobile user experience and potential SEO penalties.
Solution: Set the viewport width in the HTML to make the site responsive.

Slow Page (HTML) Load Speed

Problem: HTML pages take too long to load due to large file sizes or server issues.
Impact: Higher bounce rates, poor user experience, and lower search rankings.
Solution: Optimize code, compress resources, and improve server response times.

Addressing these errors will improve your site’s functionality, ensure search engines can efficiently crawl and index your pages, and enhance user experience, leading to better search rankings and performance.

Warnings

Warnings indicate potential areas of concern that, while not immediately critical, could impact your website’s SEO and usability if left unresolved. These are opportunities to fine-tune your site’s technical setup and ensure optimal performance in search results.

Broken External Links

Problem: External links point to non-existent or unreachable web pages.
Impact: Reduces user trust and may impact SEO if search engines crawl these broken links.
Solution: Regularly audit and update or remove broken external links.

Broken External Images

Problem: External images fail to load due to broken URLs or removed files.
Impact: Poor user experience and potential negative impact on the visual appeal of your content.
Solution: Ensure all external image URLs are valid and consider hosting important images locally.

Links Lead to HTTP Pages for HTTPS Site

Problem: Internal or external links direct users to HTTP pages while your site uses HTTPS.
Impact: Security warnings in browsers and a possible drop in rankings due to mixed content.
Solution: Update all links to point to the HTTPS versions of the pages.

Short Title Element

Problem: Title tags are too short and fail to adequately describe the page content.
Impact: Missed SEO opportunities and reduced click-through rates.
Solution: Write descriptive, keyword-optimized titles that are at least 50–60 characters.

Long Title Element

Problem: Title tags are too long and may be truncated in search results.
Impact: Lower visibility in SERPs and potential miscommunication of content relevance.
Solution: Ensure title tags are concise, around 50–60 characters, including keywords.

Missing H1

Problem: The page lacks an H1 header, which is crucial for content structure and SEO.
Impact: Search engines may struggle to understand the main topic of the page.
Solution: Add a clear and relevant H1 tag that reflects the page’s primary focus.

Duplicate Content in H1 and Title

Problem: The content in the H1 tag is identical to the title tag.
Impact: Missed opportunities for keyword variation and diminished relevance signals to search engines.
Solution: Differentiate the H1 and title tag by varying wording and including related keywords.

Missing Meta Description

Problem: No meta description is present, leaving search engines to generate one automatically.
Impact: Missed opportunity to control how your page is described in SERPs, potentially reducing click-through rates.
Solution: Write unique, engaging meta descriptions for each page to improve SEO and encourage clicks.

Too Many On-Page Links

Problem: The page contains an excessive number of links.
Impact: Dilutes link equity and overwhelms users, leading to poor user experience.
Solution: Audit and reduce the number of on-page links to focus on the most important ones.

Temporary Redirects

Problem: Temporary (302) redirects are used instead of permanent (301) redirects.
Impact: Search engines may not transfer SEO value properly, leading to lower rankings.
Solution: Replace temporary redirects with 301 redirects when permanent page moves are intended.

Missing ALT Attributes

Problem: Images lack ALT text, which is used to describe images for search engines and visually impaired users.
Impact: Missed SEO opportunities and accessibility issues.
Solution: Add relevant ALT attributes to all images.

Low Text to HTML Ratio

Problem: There is too much HTML code compared to the amount of visible content.
Impact: May slow down load times and reduce content relevance for search engines.
Solution: Minify HTML and ensure there is sufficient high-quality content on each page.

Too Many URL Parameters

Problem: URLs contain numerous parameters, which can cause issues for search engines.
Impact: Search engines may struggle to index the content properly, and tracking parameters could be confusing.
Solution: Simplify URLs by reducing parameters and using SEO-friendly URL structures.

Missing Hreflang and Lang Attributes

Problem: The page lacks hreflang and lang attributes that specify the language and region targeting.
Impact: Search engines may not display the correct language version of your page to users in different regions.
Solution: Add hreflang and lang attributes to specify language and regional targeting.

Encoding Not Declared

Problem: The page does not declare a character encoding standard.
Impact: Browsers may not display the content correctly, leading to usability issues.
Solution: Declare the correct character encoding, such as UTF-8, in the page’s HTML header.

Doctype Not Declared

Problem: The HTML document does not declare a DOCTYPE.
Impact: Browsers may render the page incorrectly, affecting user experience and accessibility.
Solution: Add the correct DOCTYPE declaration at the beginning of the HTML document.

Low Word Count

Problem: Pages have insufficient content to be deemed valuable by search engines.
Impact: Lower rankings and decreased relevance for targeted keywords.
Solution: Add meaningful, high-quality content to each page.

Incompatible Plugins Used

Problem: The website uses plugins incompatible with all browsers or devices.
Impact: Poor user experience and potential SEO penalties, particularly for mobile users.
Solution: Remove or replace incompatible plugins with modern, responsive alternatives.

Frames Used

Problem: The page uses outdated frames and is unsupported by all search engines.
Impact: Search engines may be unable to crawl and index the content within frames.
Solution: Replace frames with modern web design elements like divs and CSS.

Underscores in URL

Problem: URLs contain underscores, which could be better for SEO.
Impact: Search engines treat underscores as part of a word, reducing keyword relevance in URLs.
Solution: Use hyphens instead of URL underscores for better readability and SEO.

Nofollow Attributes in Outgoing Internal Links

Problem: Internal links are marked with a nofollow attribute, which prevents search engines from following them.
Impact: Wasted link equity and reduced crawl efficiency.
Solution: Remove nofollow attributes from internal links unless there is a specific reason to block search engines from following them.

Sitemap.xml Not Specified in Robots.txt

Problem: The robots.txt file does not specify the location of the sitemap.xml.
Impact: Search engines may miss the sitemap, leading to inefficient crawling.
Solution: Add the sitemap location to the robots.txt file.

Sitemap.xml Not Found

Problem: No sitemap.xml file is available for the website.
Impact: Search engines may struggle to discover and index all pages efficiently.
Solution: Create and submit a sitemap.xml file to search engines.

HTTPS Encryption Not Used

Problem: The website does not use HTTPS encryption.
Impact: Lower rankings, potential browser security warnings, and reduced user trust.
Solution: Implement an SSL certificate to secure the site and use HTTPS for all pages.

No SNI Support

Problem: The server does not support Server Name Indication (SNI), which allows multiple SSL certificates on the same IP address.
Impact: HTTPS may not work properly for some users.
Solution: Upgrade the server to support SNI.

HTTP URLs in Sitemap.xml for HTTPS Site

Problem: Sitemap.xml contains HTTP URLs for a website that uses HTTPS.
Impact: Confusing search engines and creating security issues.
Solution: Update all URLs in the sitemap to use HTTPS.

Uncompressed Pages

Problem: Pages are not compressed, leading to slower load times.
Impact: Poor user experience and lower search engine rankings due to slow performance.
Solution: Enable Gzip or Brotli compression on the server to reduce page size.

Blocked Internal Resources in Robots.txt

Problem: Critical internal resources (like CSS or JavaScript files) are blocked in the robots.txt file.
Impact: Search engines may not fully understand or render the page correctly.
Solution: Remove unnecessary blocks from the robots.txt file.

Uncompressed JavaScript and CSS Files

Problem: JavaScript and CSS files are not compressed, leading to slower page load times.
Impact: Poor user experience and potentially lower rankings due to slow performance.
Solution: Compress JavaScript and CSS files using Gzip or Brotli.

Uncached JavaScript and CSS Files

Problem: JavaScript and CSS files are not cached, causing longer load times on repeat visits.
Impact: Reduced user experience and slower load times, impacting SEO.
Solution: Implement caching for these files to improve performance.

Too Large JavaScript and CSS Total Size

Problem: The combined size of JavaScript and CSS files needs to be bigger, leading to slow loading times.
Impact: Increased load times negatively affect user experience and SEO.
Solution: Minimize and combine JavaScript and CSS files where possible.

Too Many JavaScript and CSS Files

Problem: The page loads an excessive number of JavaScript and CSS files.
Impact: Increases page load times, hurting user experience and rankings.
Solution: Combine and minimize files to reduce the number of requests.

Unminified JavaScript and CSS Files

Problem: JavaScript and CSS files are not minified, which adds unnecessary weight to the page.
Impact: Slower load times and poor SEO performance.
Solution: Minify these files to remove excess code and reduce page size.

Too Long Link URLs

Problem: URLs are excessively long, often containing unnecessary parameters or elements.
Impact: Poor user experience and reduced SEO efficiency, as shorter URLs tend to perform better.
Solution: Simplify and shorten URLs by removing unnecessary characters or parameters.

By resolving these warnings, you can fine-tune your website’s SEO, avoid potential pitfalls, and ensure that your site performs well in both search engine rankings and user engagement.

Notices

Notices highlight minor issues or areas for improvement that, while not urgent, can affect your website’s overall SEO and user experience if left unchecked. By addressing these notices, you can optimize your site further and prevent these minor issues from escalating into more serious problems.

Multiple H1 Tags

Problem: A page contains more than one H1 tag, which can confuse search engines about the page’s primary focus.
Impact: May dilute the SEO value of the primary H1 tag and reduce the clarity of the page’s structure.
Solution: Ensure each page contains only one H1 tag that accurately reflects the content’s main topic.

Blocked from Crawling

Problem: Some pages or resources are blocked from being crawled by search engines, either by robots.txt or meta tags.
Impact: Search engines cannot index or rank blocked content, reducing visibility.
Solution: Review robots.txt and meta tags to ensure important content is not unintentionally blocked.

URLs Longer than 200 Characters

Problem: URLs are excessively long, often including unnecessary parameters or lengthy descriptions.
Impact: Long URLs can be difficult for users to read and may negatively affect SEO.
Solution: Shorten URLs by removing unnecessary parameters and creating concise, descriptive URLs.

Nofollow Attributes in Outgoing External Links

Problem: External links are marked with a nofollow attribute, preventing search engines from following these links.
Impact: You may miss out on passing link equity to trusted external resources.
Solution: Use nofollow only for untrusted or non-relevant external links, and remove the attribute for high-quality, trusted sources.

Robots.txt Not Found

Problem: The website does not have a robots.txt file.
Impact: Search engines may waste resources crawling unimportant or restricted pages, leading to inefficient indexing.
Solution: Create a robots.txt file to guide search engines on which pages to crawl and which to ignore.

Hreflang Language Mismatch Issues

Problem: Hreflang tags need to match language or region codes.
Impact: Search engines may serve the wrong language version of a page to users, reducing the relevance of your content.
Solution: Correct the hreflang values to match the intended language and region.

No HSTS Support

Problem: The website does not use HTTP Strict Transport Security (HSTS), which enforces the use of HTTPS.
Impact: Users may still access the site over HTTP, potentially causing security risks and lower trust.
Solution: Enable HSTS to ensure all users are directed to the HTTPS version of your site.

Orphaned Pages (Google Analytics)

Problem: Pages tracked in Google Analytics are not linked to other internal pages on the site.
Impact: Orphaned pages may not be easily discoverable by users or search engines, reducing their visibility.
Solution: Ensure all pages are linked within the site to improve internal linking and crawlability.

Orphaned Sitemap Pages

Problem: Pages listed in the sitemap are not linked to other pages on the website.
Impact: Search engines may find these pages through the sitemap, but they could still be considered low-value due to the need for internal links.
Solution: Add internal links to these pages to improve crawlability and user access.

Blocked by X-Robots-Tag: noindex HTTP Header

Problem: The X-Robots-Tag blocks Pages from indexing in the HTTP header.
Impact: Search engines will not index these pages, preventing them from appearing in search results.
Solution: Review the X-Robots-Tag settings and unblock any pages that should be indexed.

Blocked External Resources in Robots.txt

Problem: External resources like CSS or JavaScript files are blocked in the robots.txt file.
Impact: Search engines may not be able to render pages properly, which could impact rankings.
Solution: Unblock critical external resources in the robots.txt file to ensure proper rendering.

Broken External JavaScript and CSS Files

Problem: External JavaScript or CSS files are missing or broken.
Impact: This can affect the functionality and appearance of your website, leading to a poor user experience.
Solution: Replace or fix the external JavaScript and CSS files to restore functionality.

Page Crawl Depth More than 3 Clicks

Problem: Pages are buried deep within the website, requiring more than three clicks.
Impact: Pages too far from the homepage may not be crawled frequently or rank well.
Solution: Flatten the site structure by linking important pages closer to the homepage.

Pages with Only One Internal Link

Problem: Some pages are linked from only one other page on the site.
Impact: These pages may receive less link equity and are harder for users and search engines to discover.
Solution: Add more internal links to these pages to increase their visibility and SEO value.

Permanent Redirects

Problem: The site uses permanent (301) redirects, which are correctly implemented but should be regularly reviewed.
Impact: While 301 redirects pass link equity, too many redirects can slow down performance.
Solution: Regularly audit redirects and eliminate any unnecessary chains or loops.

Resources Formatted as Page Links

Problem: Non-page resources (e.g., PDFs, images) are linked as HTML pages.
Impact: Misleading anchor text and expectations can lead to poor user experience.
Solution: Clearly label non-page resources and consider embedding or handling them differently.

Links with No Anchor Text

Problem: Links on the page need descriptive anchor text.
Impact: Search engines rely on anchor text to understand link relevance so that missing text can hurt SEO.
Solution: Add meaningful anchor text to all links to improve clarity and SEO.

Links with Non-Descriptive Anchor Text

Problem: Links use generic text like “click here” or “read more” instead of descriptive keywords.
Impact: Missed opportunities to provide context for both users and search engines.
Solution: Replace non-descriptive text with keyword-rich, relevant anchor text.

External Pages or Resources with 403 HTTP Status Code

Problem: External pages or resources return a 403 (forbidden) status code, which is inaccessible.
Impact: Users and search engines cannot access these external resources, affecting user experience.
Solution: Check the external resources or contact the website owners to resolve access issues.

This collection of notices reflects potential issues that are generally less severe but should still be addressed to maintain good SEO practices and a strong user experience. Regular auditing and proactive maintenance will help prevent these issues from becoming more critical.

Conclusion

Addressing the technical aspects of SEO is crucial to ensuring your website performs at its best for users and search engines. By resolving errors, addressing warnings, and proactively managing notices, you can maintain a healthy, high-performing website that ranks well and provides a seamless user experience.

To uncover and resolve these issues, various site audit tools are available. Popular tools like SEMrush Site Audit, Ahrefs Site Audit, and Screaming Frog can help you identify technical SEO problems, monitor your site’s health, and guide your optimization efforts. Regularly auditing your website with these tools will keep your SEO on track and help you avoid potential issues before they impact your rankings and traffic.