Each mistake below is quiet: it doesn't throw an error, your site still loads fine, and nothing looks obviously broken. But each one can cap how well a page ranks or how often it gets clicked. We built a free tool for each one, so you can check your own pages in a couple of minutes. New to SEO? Our plain-language guide covers the basics these mistakes assume you already know.
01 Broken or missing canonical tags
No canonical tag leaves Google to guess which version of a URL is the "real" one. Multiple canonical tags, a relative URL, or a tag placed outside <head> can all get ignored or misread, sometimes splitting ranking signals across duplicate URLs instead of consolidating them.
02 Bad robots.txt rules
A single misplaced Disallow: /, or a rule that accidentally blocks CSS and JS files Google needs to render your page, can quietly keep entire sections out of the index. It's rarely intentional, and it's easy to miss because the site itself still works fine for visitors.
03 Missing or invalid structured data
Schema markup is how you tell Google what a page actually is, an article, a product, an FAQ, so it can show richer results. Missing required fields or using deprecated properties means you lose out on rich snippets even if the visible content is perfectly fine.
Validate your schema →04 Skipped heading levels
Jumping from an H1 straight to an H4, using multiple H1s on one page, or leaving headings empty makes the page's structure harder for both crawlers and assistive technology to parse, even though it can look totally normal visually.
Check your heading outline →05 Truncated titles and descriptions
A title tag or meta description that's too long gets cut off with an ellipsis in the search results, sometimes mid-word, right before the part that would have convinced someone to click. This is invisible until you actually preview the snippet.
Preview your snippet →06 Invalid or incomplete XML sitemaps
Malformed XML, bad date formats, or duplicate URLs in your sitemap don't necessarily stop your site from being crawled, but they make your sitemap a less reliable signal, and a large enough error can cause Search Console to reject the whole file.
Validate your sitemap →07 Broken hreflang tags
Invalid language or region codes, missing return tags, or duplicate hreflang entries can confuse Google about which language or country version of a page to show, sometimes surfacing the wrong version to the wrong audience.
Check your hreflang tags →08 Keyword cannibalization
When two or more of your own pages target the same keyword, they compete with each other instead of one page building clear authority, which can hold both down in the rankings. It's not always bad (sometimes it's intentional), but unnoticed cannibalization is a common, self-inflicted ceiling on traffic.
Catching these once isn't the hard part, catching them again next month is
Weeklift connects to your real Search Console data and emails you a weekly digest, so if something like this creeps back in, you'll know before it costs you three months of traffic.
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