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40 Technical SEO Mistakes — SEMrush Study

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40 Technical SEO Mistakes — SEMrush Study

Elena Terenteva
40 Technical SEO Mistakes — SEMrush Study

Performing a complete site audit is a complicated and ongoing process that includes dozens of checkpoints and diverse knowledge. This proves, once again, that creating and supporting a vigorous and prosperous website can be a difficult quest for beginners and sometimes even for experienced specialists.

There are no perfect websites without any room for improvement. Hundreds and even thousands of issues might appear on your website. So which issues do you really need to focus on first?

We decided to find some answers by conducting a study on the frequency with which SEO mistakes appear on websites. We collected anonymous data on 100,000 websites and 450 million pages using the SEMrush Site Audit tool to determine the most common on-site technical and SEO mistakes and issues.

This year we have decided not to concentrate solely on common mistakes, but to provide as much information as possible. So below you will see statistics on 40 checks, divided into three big groups:

  • Crawlability

  • Technical SEO

  • On-page SEO

Also, we have changed our methodology a little bit and added a new dimension -- issues’ severity level. Every issue is assigned a severity level from 1 to 5, where 5 is the highest. An issue’s severity level reflects not just the effect of certain mistakes on rankings, but also their impact on your site's overall performance and user-friendliness. We added this metric because some mistakes appear on websites very rarely, but they might have a high severity level, and we don’t want you to overlook them.

The data on the frequency and severity of issues will provide you with complete information about specific errors and will allow you to learn about technical SEO risks and evaluate the worthwhileness of your efforts during the site audit process.

And now let’s get to the point!


Although SEMrush Site Audit has 60+ checks in its arsenal, we have chosen the 40 above and excluded checks for HTTPS and hreflang implementation. If you would like more information on these exclusions, you can find it in our recent research studies:

13 Most Common Hreflang Mistakes - SEMrush Study

10 HTTPS Implementation Mistakes - SEMrush Study

While the above information is helpful, we have prepared even more for you! Last year our infographic was supported by a huge post that included descriptions of analyzed mistakes, but they were brief because it is hard to compress data on 19 serious mistakes -- their impact on rankings and user experience, along with explanations of how to fix them - in one blog post. So this year we are releasing a complete PDF guide: The Ultimate Site Audit with SEMrush, which includes information about the ‘nature’ of each of the errors discussed, their impact on your website’s health and tips on how to fix them. Stay tuned!

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Elena Terenteva

SEMrush employee.

Elena Terenteva, Product Marketing Manager at SEMrush. Elena has eight years public relations and journalism experience, working as a broadcasting journalist, PR/Content manager for IT and finance companies.
Bookworm, poker player, good swimmer.

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