7 Most Common Website Errors That Affect SEO

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Having a website is crucial for any business today. But it‘s not enough to just have any website – you need one that provides a great user experience and is optimized for search engines.

SEO (search engine optimization) is key to getting your site found online. It involves making changes to your website to improve rankings on search engines like Google. There are many factors that go into SEO, and if you make mistakes, it can negatively impact your rankings.

In this comprehensive guide, we‘ll dive into the 7 most common website errors that affect SEO and how to fix them. Avoiding these pitfalls will help your website put its best foot forward in search results!

The first website error to avoid is broken links. These are links that lead to 404 "Page Not Found" errors when clicked on.

Broken links frustrate users who click on them expecting to find information. More importantly for SEO, they signal technical issues to search engines. Google specifically looks at broken links as a sign of poor website quality and maintenance.

How big of an issue are broken links? One survey conducted by Siteimprove analyzed 135 Fortune 500 company websites. Here were the results:

  • 61% had over 100 broken links
  • 18% had over 1,000 broken links
  • 5% had a shocking 10,000+ broken links!
![Broken links survey results](broken-links-survey.png)
Source: Siteimprove

Clearly broken links are common, but that doesn‘t make them any less problematic. Let‘s look at how to find and fix them.

The first step is identifying broken links on your site. Here are some ways to check:

  • Link checker tools: Use a specialized tool like Screaming Frog SEO Spider or Ahrefs to crawl your site and identify broken links.

  • Google Search Console: Google Search Console shows indexed pages on your site that return 404 errors. Check the "Crawl Errors" section.

  • Manual checks: Manually click through a sample of links on important pages to make sure they work. Focus on links in navigation, content, sidebars etc.

Once you‘ve compiled a list of broken links, it‘s time to fix them!

Here are some ways to address broken links:

  • Remove links entirely: For unimportant links that no longer matter, deleting the link altogether is the easiest option.

  • Update the URL: If the linked page still exists but has a new URL, update the link to the working URL.

  • Redirect links: For links you want to keep, redirect them to a working page using a 301 permanent redirect. This passes link equity and signals the new URL.

  • Fix technical issues: Determine if server errors, domain expirations etc. are causing certain links to break and address those problems at the source.

  • Reach out: If an external site you link to has removed a page, reach out and ask them to fix or redirect the link to a working URL if possible.

Fixing broken links should be an ongoing part of your website maintenance. Run link checks regularly and stay on top of errors as they pop up.

2. Invalid TLS Certificate

Another technical issue that can impact SEO is an invalid TLS certificate.

TLS (Transport Layer Security) certificates enable HTTPS on your site and signal to browsers that it is secure. They were formerly known as SSL certificates.

Here‘s a look at the differences between HTTP vs HTTPS:

  • HTTP – Unencrypted data transfer between browsers and servers. URLs start with "http://"

  • HTTPS – Encrypted data transfer using TLS/SSL certificates. URLs start with "https://"

Google has prioritized HTTPS-enabled sites in search rankings since 2014.

So what happens if your certificate is invalid? Visitors will see security warnings that your site is unsafe. Many will leave without trusting your site.

You‘ll also miss out on SEO benefits of HTTPS without a valid certificate installed and enabled sitewide.

Invalid TLS certificate errors happen for reasons like:

  • Expired certificate – Certs must be renewed every 1-2 years. Outdated ones trigger browser warnings.

  • Domain mismatch – Certificates are issued for specific domain names. If your domain name doesn‘t match, browsers show errors.

  • Improper installation – Incorrectly installing a certificate leads to invalid certificate errors.

  • Weak encryption – Old SHA-1 signed certificates are now considered insecure and can cause errors.

Follow these tips to avoid invalid TLS certificate issues:

  • Purchase from reputable CA – Stick to major certificate authorities like DigiCert for reliable certificates.

  • Verify domain names – Make sure certificate domain names match those on your site exactly.

  • Follow installation steps – Carefully follow the certificate installation instructions provided by your CA.

  • Renew on time – Mark your calendar to renew certificates before they expire.

  • Upgrade old certificates – If you have SHA-1 certificates, upgrade to newer SHA-256 certificates.

Taking these steps will help ensure your site maintains a valid TLS certificate and the SEO benefits of HTTPS.

3. Slow Page Speed

Site speed is another important consideration for SEO and user experience. Pages that load slowly lead to high bounce rates and send the wrong signals to search engines.

According to Think With Google, here‘s the impact of page load time on mobile bounce rate:

  • 1 second – Average bounce rate of 26%
  • 3 seconds – Average bounce rate of 38%
  • 5+ seconds – Average bounce rate of 55%
![Page load time impact on bounce rate](page-speed-bounce-rate.png)
Source: Think With Google

In 2010, Google incorporated page speed as an official ranking factor. Since then, they have emphasized the importance of fast-loading websites many times.

Use Google PageSpeed Insights and WebPageTest to measure the load speed of your site.

Common causes of slow page speed include:

  • Large, unoptimized images – Images should be compressed, resized and lazy loaded
  • Excessive server requests – Reduce resources like scripts loaded on each page
  • Overuse of plugins – Each plugin applied to your site can slow it down
  • Poor hosting infrastructure – Upgrade to fast servers and CDN hosting
  • Non-cached pages – Implement browser caching and a content delivery network (CDN)

Here are some ways to speed up site load times:

  • Optimize images – Compress, lazy load and serve images from a CDN
  • Enable caching – Set up server and browser caching for static resources
  • Minify resources – Minify CSS, JavaScript and HTML files to reduce their size
  • Limit redirects – Redirects delay page rendering; keep them to a minimum
  • Upgrade hosting – Switch to a fast hosting provider optimized for speed

Improving your web page load speed should be an ongoing effort. Monitor speed using the tools mentioned above and fix issues as they arise. Faster sites lead to lower bounce rates, better user experience and improved organic search rankings.

4. Lack of Mobile Optimization

Given the popularity of smartphones today, having a mobile-friendly website is no longer optional – it‘s a must for SEO and usability.

As of July 2019, over 50% of web traffic worldwide came from mobile devices. And that number continues rising each year.

Failing to optimize your website for mobile hurts the experience for these visitors. Pages with tiny text, broken navigation, and other mobile issues cause frustration and drive users away.

In 2015, Google made mobile-friendliness a ranking factor for mobile searches. Specifically, they target issues like:

  • Small tap targets
  • Content wider than the screen
  • Interspersed vertical and horizontal scrolling
  • Pages that require zooming to read text

Running your site through Google‘s Mobile-Friendly Test shows you these types of problems.

Here are some tips to make your site mobile-friendly:

  • Use a responsive design – Make your theme adjust layout based on screen sizes
  • Size content appropriately – Use relative units like EM or percentages for things like font size
  • Avoid interstitials – Don‘t block content with pop-ups and overlays
  • Check speed – Optimize images and resources for fast mobile load times
  • Enable taps – Make buttons and touch targets large enough for tapping
  • Style navigation – Use an icon menu instead of text links in top navs

Optimizing your site for mobile should be a top priority today. You‘ll provide a better experience for the majority of your visitors while avoiding mobile-friendliness penalties from Google.

5. Duplicate Content

Duplicate content on a website refers to substantive blocks of identical or near-identical content. This is often seen on:

  • Product description pages
  • Category archives
  • Support documentation
  • Store locators
  • Corporate boilerplate text

Search engines like unique, original content. When they crawl pages with duplicate content, it causes a few issues:

  • Difficulty determining which URL to index and rank for relevant keywords
  • Diluted link equity between duplicate versions instead of the original
  • Bloat to their indexes from crawling the same content on multiple URLs

In small doses, duplicate content doesn‘t do much harm. But excessive duplication signals a lack of unique value to search bots. At worst, Google may slap a manual action penalty on your site for extreme cases.

Here are some common causes of duplicate content:

  • Content management system templates outputting identical text across pages
  • Republishing the same content across sections of your site
  • Scraping or copying content from other websites
  • Generating event pages, store listings etc. from the same database content

Before duplicate content gets out of hand:

  • Consolidate content – If the same content appears in multiple sections of your site, pick one section that‘s most relevant and delete duplicates.

  • Re-word copies – Add some unique text and stats to product pages and other areas where some level of duplication is unavoidable.

  • Implement 301s – Redirect duplicate URLs to a single version and pass on link equity using 301 redirects.

  • Use canonical tags – Add rel=canonical tags to signal the original version of duplicate pages.

  • Generate unique metadata – Even if underlying content is duplicate, customize titles, descriptions and headings to seem unique.

  • NoIndex copies – Use meta noindex tags to hide duplicated pages from search engine indexing.

Duplicate content takes regular audits and site cleanup to prevent. But eliminating it will improve your site‘s uniqueness and prevent dilution of search rankings.

Most SEOs focus heavily on building backlinks from high-quality websites to earn trusts in Google‘s eyes. But low-quality and spammy backlinks can actually harm your site.

These "toxic backlinks" come from a few common sources:

  • Link networks – Networks created solely to trade links between sites for SEO.

  • Spun content – Automated tools generate content by ripping and rearranging content from other pages.

  • Paid links – Buying backlinks from low-quality sites offering this service.

  • Comment spam – Irrelevant links left in blog post comments and forums.

Google applies an algorithmic filter to devalue toxic backlinks like these. The more you accumulate, the more your site gets associated with black hat practices.

Penguin is the best known Google algorithm focused on suspicious backlinks. Since launching in 2012, it has impacted many sites engaged in aggressive link building tactics.

Beyond direct algorithmic filters, Google may take manual actions against your site for unnatural link profiles:

  • Link schemes – Creating linked networks solely to manipulate PageRank
  • Buying or selling links – Purchasing links from or selling links on untrusted websites
  • Webspam reports – Competitors reporting your site for suspicious backlink building

Checking your backlink profile periodically helps avoid toxic links. Here‘s how:

  • Backlink analysis – Use Ahrefs, Semrush or Moz to analyze your backlink sources
  • Google Search Console – Check your manual/algorithmic penalty status

Address any toxic links you find:

  • Disavow links – Use Google‘s disavow tool to signal you don‘t want specific backlinks counted.

  • Deindex pages – Remove pages getting lots of spammy links from Google‘s index with a noindex tag.

  • Update anchor text – Contact sites to change your backlink anchor text if it uses over-optimized keywords.

  • Fix technical issues – Remove comment spam, fix broken contact forms etc. that allow poor links.

Conduct backlink audits regularly and distance yourself from questionable links pointing to your site. This protects your site from both algorithmic and manual penalties.

7. Unresolved Crawl Errors

The final technical issue to avoid is crawl errors. These prevent Googlebot from fully indexing your site – reducing pages findable in search results.

Some common crawl errors include:

  • 404 errors – Pages returning 404 not found errors when Google tries to access them.

  • Redirect loops – Chains of redirects that circle back to the same page.

  • Blocked resources – Resources like images that get blocked from crawling.

  • Authentication – Pages like member portals requiring logins that bots can‘t access.

  • Unsupported content – Things like JavaScript-heavy pages without HTML snapshots for bots.

You can identify crawl errors for your site in Google Search Console:

![Google Search Console crawl errors](google-search-console-crawl-errors.png)

Here are tips to address crawl errors:

  • Fix broken pages – Redirect or remove URLs getting 404s; don‘t leave dead links.

  • Allow bots access – Make sure your robots.txt file and meta noindex tags aren‘t blocking Google.

  • Consolidate URLs – Use 301 redirects and canonical tags to consolidate URLs instead of allowing duplicate content.

  • Create structured data – Add structured data so Google can extract info from complex pages.

  • Render JavaScript – Pre-render JavaScript using or platforms so bots index JS content.

Crawl errors reduce the number of pages Google can access and index from your site. Eliminating them helps maximize your exposure in search results.


Having a strong technical SEO strategy is crucial for ranking well in search engines today. Avoiding common website errors like broken links, duplicate content, crawl errors and more ensures your site sends the right signals to Google.

Regularly monitor your website for these 7 issues using tools like Google Search Console. Staying on top of errors helps provide the best user experience and maximize your SEO efforts.

Fixing problems as they occur keeps your site running smoothly. Pair these technical best practices with high-quality content and smart link building to fully optimize your web presence.

Now that you know the most common website errors affecting SEO, you can proactively improve your site‘s health and search visibility. By creating a technical SEO checklist, you can easily stay on top of your website and avoid critical mistakes.


Written by Alexis Kestler

A female web designer and programmer - Now is a 36-year IT professional with over 15 years of experience living in NorCal. I enjoy keeping my feet wet in the world of technology through reading, working, and researching topics that pique my interest.