Hyphens, not underscores: Crawl Audit check 42

Short answer: check 42 warns when the page's URL path contains an underscore, as in /stock_count_app. Google recommends hyphens to separate words in URLs: /stock-count-app. This is one of the few URL checks where Crawl Audit's rule and Google's advice match exactly.

What Crawl Audit checks

• Pass: no underscore in the path.
• Warning: one or more underscores.

It only looks at the path, the part after the domain. Underscores in query parameters, such as ?utm_source=, don't count.

What Google says

Google's URL structure guide: "we recommend using hyphens ( - ) instead of underscores ( _ ) to separate words in your URLs", and "For historical reasons, we don't recommend using underscores". It also recommends readable words over ID numbers.

Should you change existing URLs?

• New pages: always use hyphens.
• Existing pages that get traffic: only change the slug if you also add a permanent (301 or 308) redirect from the old URL. Otherwise you lose the links and history the old URL had.
• A whole site built with underscores: a warning on this check isn't a reason for a big migration on its own. Fix it when you're restructuring anyway.

On your platform

• WordPress: slugs use hyphens by default. Check any you typed by hand in the post's URL setting.
• Shopify: edit the handle in the page's or product's SEO section. To redirect the old URL, go to Content › Menus › View URL Redirects.
• Wix: edit the slug in the page's SEO settings. Wix creates the 301 redirect for you.
• Squarespace: edit the URL slug in page settings, then add a line to URL mappings such as /old_url -> /new-url 301.
• Next.js: rename the route folder and add the old path to redirects in next.config with permanent: true.

Sources

• Google Search Central, URL structure best practices (updated 10 December 2025), checked 3 October 2026.
• Shopify, URL redirects; Wix, Setting up a 301 redirect; Squarespace, URL mappings; Next.js, redirects.