Underscores in URL

This error appears when a page's URL uses underscores as word separators instead of hyphens. Here's what it means and how to fix it.

What this error means

In URLs, word separators can be hyphens (-) or underscores (_). Although both are technically valid, Google treats them differently: hyphens tell it there's a break between words, while underscores cause it to read the joined words as a single one. This means a URL like /technical_seo may be interpreted as a single word technicalseo, while /technical-seo is correctly interpreted as two separate words. That difference can affect how Google understands the page's content and which searches it considers it relevant for. It's not a critical error, but it is considered bad practice in SEO. The recommendation to use hyphens instead of underscores comes from Google itself and is one of those basic standards worth following. This error usually appears on sites where URLs were automatically generated from file names or systems that used underscores by default, or when a typical programming convention — where underscores are common — carried over into the URLs.

Why fixing underscores in URLs matters

It's not an error that will tank your rankings overnight, but it is a bad practice worth eliminating. Fixing it is straightforward and the result is a cleaner URL structure that's easier to interpret.

Impact on SEO rankings

Google joins words separated by underscores and reads them as one, which can prevent it from correctly identifying the individual keywords in the URL. Switching to hyphens helps the search engine better interpret the page's content and can improve its relevance for the searches that matter to you.

Impact on user experience

A URL with underscores is harder to read at a glance. Hyphens act as visual spaces that separate words naturally. Underscores, on the other hand, blend in with the underline when the URL appears as a link, to the point of becoming visually invisible.

Negative signals for site quality

Using underscores in URLs is an outdated practice. It's a signal that the site's technical configuration isn't aligned with current SEO standards.

How to fix it step by step

If this error showed up in your audit, here are the steps to leave it behind.

Step 1

Identify which URLs have underscores

Ruk Audit shows you exactly which URLs use underscores as separators. Review them before touching anything and prioritize the most important ones.

Step 2

Replace the underscores in the CMS

For each affected URL, edit the slug or permalink from your CMS and replace each underscore with a hyphen. Before saving, check that the URL is still readable and descriptive.

Step 3

Set up a 301 redirect to the new URL

Once the new URL is published, set up a 301 redirect from the old one so Google and users reach the new URL without losing the authority it had already accumulated.

Step 4

Update internal links pointing to the old URL

Search your site's content for all links using the URL with underscores and replace them with the corrected version. That way you don't depend on the redirect and your internal linking stays clean.

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