10 Technical SEO Errors That Most Websites Are Struggling With

The most damaging Technical SEO errors are usually the ones that stop search engines from even seeing your page. I am talking about accidental noindex tags, blocking bots in your robots.txt file, and messing up your canonical tags so Google doesn’t know which page is the original.

You can have the best content in the world but if the crawler hits a wall before it reads a single word, you are invisible. It really is that simple.

I have been working in this industry for about 15 years now. I have seen algorithms change and “best practices” come and go like fashion trends.

But one thing stays the same. Websites break. They break in ways that are completely silent to the user but scream at the search engine bots. It is frustrating.

Most people obsess over keywords or backlinks. That stuff matters. Of course it does. But ignoring the technical foundation is like painting a house that has no walls.

So I want to walk you through the mess I see every week. These aren’t theoretical problems. These are the things that are tanking rankings right now.

The silent killer of visibility

I cannot tell you how many times I have audited a site that was “struggling to rank” only to find a noindex tag sitting in the code.

It happens more than you think. A developer pushes a staging site to live & forgets to remove the tag that discourages search engines. Suddenly the whole site drops out of the index. It is silent. The site works fine for users. You can click around and buy things. But to Google, the door is locked.

Practitioners usually recommend focusing first on issues blocking crawling or indexing. This is why.

You need to check this immediately. You can use Google Search Console to see if your submitted pages are marked as “excluded” due to a noindex tag. If they are, and they shouldn’t be, you have found your problem. It is an easy fix but a catastrophic error if left alone.

Sometimes it is not the whole site. Sometimes it is just a category of pages that someone decided didn’t need to be there. But those pages might be passing link equity to other important pages.

Canonical tags are confusing

Canonical tags are supposed to solve duplicate content issues. They tell search engines which version of a URL is the “master” copy.

But people get this wrong constantly.

I see websites where every page has a canonical tag pointing to the homepage. That tells Google that every single page on your site is just a copy of the homepage. That creates a massive indexing disaster. Or I see pages that don’t have a self-referencing canonical tag at all.

If you have example.com/page and example.com/page/ (with the slash), those are two different pages to a bot. If they load the same content, you have a duplicate content problem. They compete with each other.

You need to make sure the canonical points to the version you want to rank. It sounds technical because it is. But the logic is straightforward. Don’t make Google guess.

I remember one client who had canonicalized all their product pages to the category page because they thought it would boost the category ranking. It didn’t. It just de-indexed all their products. We fixed that in a morning and traffic jumped 40% in two weeks.

Robots.txt files block too much

Your robots.txt file is a gatekeeper. It tells bots where they can and cannot go.

The problem is that people block things they shouldn’t.

I see sites blocking their CSS and JavaScript files in robots.txt. Years ago that was fine. But now Google renders the page like a browser. If it can’t load your CSS, it sees a broken, ugly page. It might think your site is not mobile-friendly because it can’t load the styles that make it responsive.

And then there is the AI issue.

We are seeing a trend where brands are terrified of AI scraping their content. So they block GPTBot. In fact, 34% of SaaS sites block GPTBot in robots.txt. I get the fear. But blocking GPTBot renders you invisible to AI tools that hold a massive market share.

If search is moving towards generative answers, and you have told the generator to go away, you are opting out of the future of search. It is a risky move.

Speed metrics and user experience

Core Web Vitals. Everyone talks about them.

But looking at the data, most sites are still failing. We see problems with Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) everywhere.

It is usually images. Big, uncompressed images that take forever to load. Or it is JavaScript that blocks the rendering of the page.

Among sites with CSS issues, 58% have oversized CSS files and 49% use uncompressed files. That is just laziness. There are plugins and tools that minify this stuff automatically.

I think people get obsessed with getting a “100” score on the test tool. You don’t need a 100. You just need to be fast enough that users don’t leave.

If your site jumps around while it loads (that’s CLS), users click the wrong button. That is frustrating. Google knows it is frustrating. That is why it is a ranking factor.

Fix your images. Minify your CSS. It is not rocket science but it requires maintenance.

The duplicate content trap

Duplicate content is rarely malicious. It is usually accidental.

It happens when your site is accessible via HTTP and HTTPS. Or www and non-www. If you haven’t set up 301 redirects to force everyone to a single version, you have four versions of your website live.

Google is pretty smart at figuring this out. But why risk it?

Another source is faceted navigation. You know, those filters on ecommerce sites where you can sort by color, size, and price. Every combination creates a new URL.

If you don’t control this with robots.txt or canonical tags, you generate thousands of thin, duplicate pages. This wastes your crawl budget. Google spends all its time crawling your “Blue T-shirts sorted by Price Low to High” pages and ignores your new blog posts.

It is a mess to clean up once it is indexed. Prevention is better.

Broken links and 404s

Links rot. It is a fact of the web.

You link to a resource, that resource moves or dies, and now you have a broken link. Or you delete a page on your own site and forget to redirect it.

Data shows that 36% of websites have pages with 4XX errors. That is more than a third.

When a search bot hits a 404, it stops. It is a dead end. If you have too many of these, it signals that the site is poorly maintained.

It is also bad for users. Imagine clicking a link promising an answer and getting an error page. You would bounce immediately.

You need to audit your internal links regularly. I use a crawler tool to scan the site every month. It takes an hour to fix them.

Orphan pages are another issue here. These are pages that exist but have no internal links pointing to them. Search engines can’t find them unless they are in the sitemap. And even then, if you don’t link to them, you are telling Google they aren’t important.

Schema markup is often wrong

Structured data helps search engines understand what your content is. Is it a recipe? A product? A review?

But “Schema Drift” is a real problem. This happens when the data in your JSON-LD code contradicts what is visible on the page. Maybe the price changed on the page but the schema still shows the old price.

This kills your rich results. Google will penalize you for providing misleading data.

In 2026, or whatever year we are pretending it is, AI relies heavily on this data. Domains with valid Organization Schema are 3.5x more likely to be correctly identified by ChatGPT. That is a massive stat.

If you are missing schema like SiteNavigationElement, which 68% of sites are, you are making it harder for bots to understand your structure.

Don’t just copy and paste code. Validate it.

International targeting mistakes

If you run a site that serves multiple countries, hreflang tags are your best friend & your worst nightmare.

They tell Google “this page is for users in the UK” and “this page is for users in the US”.

The errors here are frequent. I see UK pages tagged as ‘en-us’. I see return tags missing. Hreflang has to be reciprocal. If page A links to page B as an alternate, page B must link back to page A. If it doesn’t, the tag is ignored.

It is tedious work to get right. It is difficult to accomodate every variation if your site structure is messy.

But when it works, it stops your US page from outranking your UK page for a user in London. That matters for conversion.

Server errors and log files

We talked about 4XX errors. But 5xx errors are worse.

A 500 error means the server failed. If Googlebot hits your site and gets a 500 error, it will come back later. If it keeps getting them, it will slow down its crawl rate. It thinks your server can’t handle the traffic.

Eventually, it might start de-indexing pages.

You need to look at your server logs. Most SEOs never look at logs. They just look at crawl reports. But logs tell you exactly what the bot experienced.

During peak traffic times, server errors often spike. You might not notice because you are asleep. But the bots never sleep. Scaling your resources is part of SEO.

Ignoring the mobile experience

I know. “Mobile-first indexing” is old news.

Yet I still see sites that treat mobile as an afterthought.

It’s not just about the design fitting the screen. It is about content parity. Does your mobile site have the same content as your desktop site?

Sometimes developers hide text on mobile to “clean up the design”. If that text is hidden, Google might not weight it as heavily. Or worse, if the internal links are hidden on mobile, Google can’t crawl the rest of the site effectively.

Intrusive pop-ups are another mobile killer. If a user lands on your page and the first thing they see is a giant newsletter signup that they can’t close, that is a bad experience. Google penalizes that.

Nearly 8 in 10 mobile searches yield zero open-web traffic now as answer engines synthesize data directly. If you want to be part of the answer, your mobile technicals must be flawless.

Final Thoughts

Technical SEO is not about checking boxes on a list. It is about health.

You can have a site that looks great and reads well, but if the technical foundation is rotten, you are building on sand. I have seen businesses try to write their way out of a technical hole. It never works.

Start with the basics. Can the bot find the page? Can it read the page? Is the page fast?

Don’t get overwhelmed by the jargon. Fix the crawl blocks. Sort out your canonicals. Speed up your images.

The industry keeps evolving. AI is changing how we think about visibility. But the need for a technically sound website isn’t going anywhere. It is the price of entry.