You can identify whether your website has HTTP 301 errors by using an online tool or plugin that checks your website for broken links or redirects. Some popular tools include Google Search Console, Screaming Frog, or Ahrefs. These tools can help identify any broken or redirected links, and allow you to see the specific URLs that are returning an HTTP 301 error.
Additionally, you can manually check for redirects by using a web browser or URL redirect checker to test each page on your website. If a page redirects to a different URL, and returns an HTTP 301 status code, then it has an HTTP 301 error.