Pages that 301 redirect to a 404

[sbb024]

We are going through a website redesign that involves changing URL's for the pages on our site. Currently all our pages are in the format domain.com/example.html and we are moving to stip off the .html file extension so it would just be domain.com/example

We have thousands of pages as the site deals with news so building a redirect for each individual page isn't really feasible. My plan is to have a generic rewrite rule that redirects any page that ends .html to the stripped off version of this. A problem I can see with this is that it will also redirect pages that don't exist.

So for example, domain.com/non-existant-page.html would 301 to domain.com/non-existant-page which would then return a 404 status.

What would the SEO repercussions be for this? Obviously if a page doesn't exist already then it shouldn't show up in the search engine indexes and shouldn't be a problem but I'm a bit worried about how old pages that currently legitimately 404 will be treated when they start to 301 redirect to a 404 instead. Not sure if there any other potential issues from this that I've missed either?

Thanks!

[davebuts]

Using the rewrite rule is fine.

There is no issue with domain.com/non-existant-page.html 301 redirecting to domain.com/non-existant-page which would then return a 404 status. If you go to anydomain.com/any-non-existing-page you will return a 404 page but this endless amount of possible pages will not be crawled by search engines because they do not exist and you (or anyone else) should not be linking to them.

With your old, legit 404 error pages, I would recommend 301 redirecting them to a relevant new page, a relevant category page, or the homepage if nothing else is suitable.

[JarnoNijzing]

I agree with Dave.

When the page redirects from a page to a 404 it's another redirect however the url mentioned does not exist so there should not be any links to it within your site. If a competitor is linking to a non existing page it's referred to external and as long as it stays like that then you should be just fine. The problem starts when you start linking to a non existing page.

So keep it clean and implement the change I would say.