[Resolved] 404 translation with main language in subfolder

Hi Eran,

thanks for your response. You misunderstood my question (a bit), but your response was golden anyway. Thanks!

I use the Kadence Theme and thus a Kadence Element to customize the content of my 404 page. Inside the Kadence Element, I wrap that custom content in a vanilla-Wordpress-reusable-Gutenberg-block to be able to use WPMLs Automatic Translation Editor to translate my custom 404 page. This way, I already have a Danish and a English 404 page. Nothing magic.
The problem, I still had, was that I wanted to control, which language the 404-page is shown in, if it is not clear from the URL, which language the visitor is browsing my website in. The default behaviour is that the 404-page is shown in the main-language, which is Danish in my case, but I want English instead. I changed your code example a bit to define the desired behaviour and quote it here for others for inspiration:

function bofy_pre_handle_404($preempt, $wp_query) {
	if ( !str_contains($_SERVER['REQUEST_URI'], '/en/')  && !str_contains($_SERVER['REQUEST_URI'], '/da/') ) {
		do_action( 'wpml_switch_language', 'en' );
	}
	return $preempt; 
}
add_filter( "pre_handle_404", "bofy_pre_handle_404", 10, 2 );

The code simply checks, whether the request URL that provoked the 404 contains a language-specific subfolder ("/da/" or "/en/") and, if not, forces English as language. The rest is default 404-handling.

Thanks again, Eran, for pointing my nose!

Best,
Maria