Why Not to 301 Redirect all 404s to Your Homepage
Our site Writers.com has a lot of 404s stretching back across its long history. As I’ve started to work to clean them up, I flirted with simply 301 redirecting every 404ing link to the homepage. (There are a few plugins that do just that.)
Fortunately, I googled a bit and found that this is not so great from an SEO standpoint. The linked article explains the reasons why not as well as any:
When you do this blanket redirect, all those URLs are treated as 404s. So none of them spread value… On top of that, by 301 redirecting all your 404 pages, you throw away the opportunity to find real errors on your site and fix them.
That leaves me in the position of manually redirecting everything, which is a bummer—and something I still haven’t gotten to in the week or two since doing this research—but it’s good to know what actually is and isn’t good practice in this case.