The first step to fixing 404 errors is to identify them. To do this there are several options:
- Google Search Console will show some 404 errors in its Index Coverage Report based on crawling URLs found in your sitemap and linked to from other websites.
- The Swerve Redirects app tracks 404 errors encountered by users in real time.
- Site Crawlers such as Screaming Frog SEO Spider will crawl your site to identify broken links found within your website