Should I use 302 redirect when user's browser is out of date?

Question

I want to show the following popup if the user browser is outdated:

I check the client browser and return a 302 redirect to MySite/ErrorPages/OutdatedBrowser page if their browser is too old.

I am using SEMRUSH and I noticed that SEMRUSH crawler gets redirected to MySite/ErrorPages/OutdatedBrowser and their audit tool is giving me warning about this redirect (it says that the page ranking will be spitted between the two pages).

1. Is it a bad practice to redirect to "outdated" browser page?
2. Should I show the "outdated" message on the same page?

The reason I decided to use the redirect option is that, the "outdated" popup is extra html that I prefer to keep out of my pages.

Answer 1

Generally, you shouldn't redirect to an entirely separate page or display an obtrusive "popup" to outdated browsers unless maybe the site/application is entirely inaccessible to those on the "outdated browser".

On most informational websites the content should still be accessible, even though it may not look as intended or be "broken" in places. If the content can still be consumed then an unobtrusive banner (on the same page) would be far more preferable.

Redirecting to a separate page (or displaying an obtrusive popup) can deliver a bad user experience and alienate the user. Particularly with today's auto-updating and update-notifying browsers, if a user is using an outdated browser it may be for good reason as they have likely taken additional steps to prevent the browser from updating. Or they are using older hardware (older OS) that does not support the newer browsers. And users in a corporate environment often don't have control over their browsers/machines so cannot simply update it.

So, if a user is using an outdated browser it is often because they can't or don't want to update it. They should still be able to consume the content if possible.

Try opening this very same website in IE

AFAICT this website only displays an "unobtrusive banner" to IE11 and early versions of Edge. Other "outdated browsers", including earlier versions of IE do not get any notification. (Maybe because it is deemed that users of these browsers should be able to update via Windows Update?) The website content can still be consumed on even ancient browsers.

I check the client browser and return a 302 redirect to ...
... the "outdated" popup is extra html that I prefer to keep out of my pages.

If you are returning a "302 redirect" then you must already be performing the browser check server-side, in which case any additional "outdated banner/popup" HTML/JS should only be served to those browsers that actually "need" it. This "extra HTML" does not need to be present in the page that is served to everyone else if you are performing this test server-side to begin with.

SEMRUSH crawler gets redirected

This would certainly seem to be an error in your browser detection script. The default action needs to be "no banner/popup". And, as @StephenOstermiller mentioned in comments, bots certainly need to be excluded.

Answer 2

How you'd technically implement it would be a thing of its own, but perhaps you could back to a separate version of the page if the browser is outdated.

In my opinion that might be a better experience if someone is browsing the web they might not want to update their browser that second because they're in the middle of a task.

As long as you make sure the separate page for outdated browsers lists the official page as the canonical URL, Google won't consider it duplicate content. Additionally, by applying the meta robots noindex tag, should be safe from unwanted indexation but Google does sometimes ignore this and index no-index pages anyways.

A 302 redirect would be appropriate.

It's saying to search engines this might not be that permanent. It might change in the future, it might change depending on who accesses it, on the device used, or the user’s location. Moreover, it shouldn't be cached.