SEO impact of changing versions (and names) of external CSS

Question

A website of mine uses a WordPress plugin for CSS minification. The plugin regenerates the CSS file on every update to the style-sheet. When it does, the plugin also changes the version and hence name of the CSS file.

If Google crawler tries to look for older versions of CSS based on the information from previously cached versions of HTML pages, 404 is returned. Will this impact SEO?

Answer 1

A 404 by itself is not necessarily a bad thing. For resources no longer available, it is the correct server response. The only scenario where a 404 is bad is if the resource needs to be found, either for indexing or rendering.

As Simon pointed out above, search engines will fetch and index a resource anew if they see a new URL. Thus, it will not impact rendering or what's been indexed.

I used to manage a Drupal website where the lead developer set up CSS files to have a random number at the end of the URL, and those numbers got dynamically regenerated every couple of weeks, to keep search engines from caching the CSS for too long, as changes were frequent. It caused issues in Pardot landing pages (a marketing automation system), but SEO was unaffected.

Related: I use the noarchive meta tag on all website content, globally. This prevents search engines from storing archived snapshots of websites. Rankings remain unaffected.

Answer 2

CSS documents focus on appearance, layout, style, and the display characteristics of the corresponding HTML elements. HTML documents primarily focus on content: headers, paragraphs, images, etc. SEO ranks are based on the content of your webpages... When you think about it, the search engine spiders are inherently more concerened about your content than the style of the page. Following this line of thinking, SEO ranks should not be affected by the CSS styles.

[note: yes, hidden values are apparently an issue with SEO, but the OP is asking about file name changes being an issue, not values within the document.]