WP Site not working properly without www prefix - php

Question

So depending on what I set the WP Settings URLs to, the site either only works properly with the www prefix or without.
Working properly with www prefix
Without www prefix
Changing the Wordpress Address and Site Address to the address without www prefix and the problem is the other way around. (blendpunkt.at is working but not www.blendpunkt.at)

Answer 1

You have to update the domain to use the variant without www using plugins like Better Search Replace, Velvet Blues Update URLs and the general settings of WordPress in the backend (Home and Site URL).
https://wordpress.org/plugins/velvet-blues-update-urls/
https://wordpress.org/plugins/better-search-replace/
Then you have to update https://wwwblendpunkt.at to https://blendpunkt.at or opposite. And also check if there are http variants.
You might also want to enforce https (using HSTS or another solution, see also https://github.com/h5bp/html5-boilerplate/blob/master/dist/.htaccess and the sections for https + www redirection and enforcing https).
Please create a full backup before using these plugins
Because as you can see www.example.com and example.com are different hostnames and cause a CORS (Cross-Origin Resource Sharing) error.
PS: This question would fit better on https://wordpress.stackexchange.com/

Answer 2

This seems to be some kind of a work-around and there might be other solutions. But in the way you ask, it does not matter for you if you use the url with or withour prefix, you just want the map to work. So it is an option to redirect all requests without www to the request with the www prefix.
Change your wordpress and site url to your domain with the www prefix.
In the root folder of wordpress when accessing it with FTP, there should be a .htaccess file. If there is no such file, you can create one (https://wordpress.org/support/article/htaccess/).
Inside of this file, right under the RewriteEngine on you insert this code:
RewriteCond %{HTTPS} off [OR]
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTP_HOST} ^(?:www\.)?(.+)$ [NC]
RewriteRule ^ https://www.%1%{REQUEST_URI} [L,NE,R=301]
This way all requests without https and/or without www will be redirect to https://www.
Another way, without having effect on the whole website, you can just create a redirect for this specific page. Adjust this code snippet to your domain and put it into the functions.php file of your theme, or alternatively create a plugin for redirects, if you have multiple of them.
add_action( 'template_redirect', function() {
if( ( is_page('kontakt') ) ) {
wp_redirect( 'https://www.yoursite.com/kontakt' );
exit();
}
});