The report was based on data from 52,000 audits conducted using the Sitechecker tool on more than 6 million webpages. The researchers separated the findings into three severity levels: critical errors (SEO issues that have a high impact on search performance), warnings (medium impact), and notices (low impact).
Some 24% of the website SEO mistakes uncovered were critical, 32% were warnings, and 44% were notices.
The most common critical error on websites is missing metatags (title, H1, or description), the analysis found.
The most common warning error is duplicate H1 tags, and the most common notice error is titles that are too short.
Check out the infographic for more findings from the report: