Custom structure permalink preventing 404

OK so after much working out what was causing this, this was caused by me not setting:

fastcgi_param PATH_INFO

Which was being set as part of the hosting setup the company I work for sets.

We found this out by tracing back the cause to the class_wp.php file in particular we found that:

if ( empty( $requested_path ) || $requested_file == $self || strpos( $_SERVER['PHP_SELF'], 'wp-admin/' ) !== false ) {

$self and $_SERVER['PHP_SELF'] were coming up as index.php for my local copy but on the hosting environment these values were matching the $requested_path.

So nothing to do with plugins etc.

It is normal behavior of WordPress to redirect users to 404 page when a post is not found.

Both should have got redirected to 404 page ideally:

• domain.com/news-opinion/non-existing-url
• domain.com/non-existing-url

It is strange that you are facing this issue. Would you mind trying the below steps (check the issue after each step):

1. Change Permalinks to the "Plain" from the Permalinks Settings Page.
2. If it doesn't work then please check that your .htaccess file contains the default WordPress Rules. If not then please add them.
3. Deactivate all the plugins.
4. Switch to default theme like Twenty-Twenty.

If you find that after trying the above steps the issue is fixed then please activate your theme and plugins back one-by-one and also reverting to your custom permalinks settings.

Hope you can get to the problem which is causing this issue.

So to confirm, on a fresh Wordpress install with that setup /non-existing-url definitely returns 404, so it's not specifically the custom permalink that's the cause.

It may be worth posting your .htaccess in case it's been modified.

However I'd suspect that one of the plugins you have is helpfully adding this feature, and I'd suggest temporarily disabling Redirection and SEOPress to see if it's them. Once you figure out which one it is you can see if there's a way to disable this specific behaviour in that plugin

If you want to, it would be easy to manually add an .htaccess rule to make /anything 404, but that puts a fix on top of a problem and will quite possibly break other things, so I agree with the point of your post which would be figure out what's doing it if possible.

EDIT: Query Monitor shows you which URL rules the current page matched against, however I don't know if it'll be useful here where there's a redirect. Worth knowing about if you don't already as it's a great tool for debugging URL rewrite issues.