Reference

Audit reference

The 45 checks CrawlStat runs after every crawl. This is the same text you see in the app’s Issues panel.

Errors

Broken for visitors or search engines. Fix these first.
Server error (5xx)SEOClient error (4xx)SEOURL could not be fetchedSEOPage links to a broken URLSEORedirect loopSEOCanonical points at a broken URLSEOMixed content on an HTTPS pageSEOLink with no accessible nameAccessibilityButton with no accessible nameAccessibilityForm field with no labelAccessibilityARIA reference points at nothingAccessibilityPage does not declare a languageAccessibility

Warnings

Costing you rankings or crawl budget.
Redirect chainSEOInternal link to a redirectSEOMissing titleSEODuplicate titleSEOTitle too longSEOMissing meta descriptionSEODuplicate meta descriptionSEOMissing H1SEONoindex page receives internal linksSEOBlocked by robots.txt but linked internallySEOHreflang missing a return linkSEOHreflang block does not list the page itselfSEOInvalid hreflang language codeSEODuplicate contentSEOImage missing alt textSEOOrphan pageSEOHTTP URL on an HTTPS siteSEODuplicate element idAccessibilityInvalid ARIA roleAccessibilityPositive tabindexAccessibilityFrame with no titleAccessibility

Notices

Worth a look; often intentional.
Title too shortSEOMeta description too longSEOMeta description too shortSEOMultiple H1sSEOMissing canonicalSEOCanonicalised to another URLSEONoindex pageSEONear duplicate contentSEOHeading level skippedAccessibilitySlow responseSEOOversized imageSEOPage buried deep in the siteSEO