How important is it to fix 500 and 404 errors you find in Production web services?

Question

How important is it to fix 500 and 404 errors you find in Production web services?

For mature products, is it a best practice to hunt down and repair all 404/500 errors that you find customers come across?

Answer 1

In general, if the user can get to the error pages by navigating via a link, or any other reasonable UI element: Yes, definitely fix them (or remove the links). There's simply no reason to show an error message to a user instead of the correct content. If the page has gone, I'm sure everybody would prefer no link rather than a broken one.

500 errors (or really, all 5xx ones) on unreachable URLs indicate an error in your code, and should be handled like any other (not particulary important) bug - i.e. fix them.

404 errors (and all other 4xx ones) on resources the user cannot reach are intentional and correct. You may, however, log/analyze them to find broken incoming links, and should offer a good error page (with a link to the homepage and a search bar) in any case.