Will page be marked as 404 if you replace country specific letters from url?

[Optimal_Strategies]

What I'm reffering to is replacement of Polish characters from i.e "ł" to "l" or "ę" to "e". I believe it relates same way as other similar Slavic languages.

[effectdigital]

Not a problem. Just remember that web user's browsers, Google's crawlers and SEO-tool crawlers all tend to react to certain factors a little differently

Never lose sight on pleasing Google first. Never lose sight that Google wants to please users the most (as without them, all their ad-revenue disappears)

[Optimal_Strategies]

Thank you for rapid and concise response. Relying what you provided here, I don't think that I have to replace url's at all. That saves a bit of work and since Google is fine with that, I'm fine too.

As there wasn't that many url's with polish characters, at least I have a choice to use them (or not) in future.

Again, thanks for great response.

[effectdigital]

If you replace Polish characters with English characters in your URL strings, as long as you redirect the old URLs (containing foreign / Slavic characters) properly to the new ones (Latin / English alphabet characters only) and as long as you update all internal and external links to those old URLs (so Google won't navigate to them internally, or from across the web) then you shouldn't get 404s

The real question is, why would you undo the 'proper' native Slavic URL encoding?

Google say you are fine to use those characters in URLs:

https://searchengineland.com/google-using-non-english-urls-non-english-websites-fine-294758

"This includes non-Latin characters in your URLs. John Mueller said “as long as URLs are valid and unique, that’s fine.” He added, “So to sum it up, yes, non-English words and URLs are fine, [and] we recommend using them for non-English websites."

Most modern web browsers will handle these characters without throwing an exception, obviously if you were to go back to ancient browsers that no one uses any more like IE1 - IE8, or NetScape or something like that - you might have problems

Google try to reflect what they think most browsers are capable of handling. Google won't show errors on such URLs if they believe that most people on most browsers would see the content correctly

Look at this Google search:

https://www.google.co.uk/search?q=%C4%99

Result #1:

Ę - Wikipedia
https://en.wikipedia.org/wiki/Ę
Ę is a letter in the Polish, Lithuanian and Dalecarlian alphabets. It is used in Navajo to represent the nasal vowel [ẽ]. In Latin, Irish, and Old Norse palaeography, ...
‎In Polish · ‎History · ‎Alternations · ‎In Lithuanian

Result number 1 on Google contains the character "Ę" in the URL, so you know Google can index these URLs and is doing so. Not only does it not result in an error, but Google willfully chooses to index such URLs when relevant queries are processed

Let's look at another Google result, the Polish word for "lamb" aka a young sheep which you can eat!

https://www.google.co.uk/search?q=jagni%C4%99

Loads of the results contain "ę" in the URL. Seems fine to me

It may be true that Moz and some other SEO crawlers have issues interpreting some foreign characters in the URL string (ę - is but one example). But that's not true for most modern web browsers or for Google. IMO that says Moz needs and update and you don't need to change your site. Aim for what makes Google happy