Google's John Mueller explains when it's useful to fix 404 errors from inbound links and when it's a waste of time ...

Google On 404 Errors And Ranking Drops Google's Gary Illyes answered a question about a ranking drop that appeared to be connected to 404 page not found errors ...

During the post-migration phase of updating our JavaScript library, we noticed random 404 errors in our SEO tools and Google Search Console. The strange part?