HTTP status code 301 - Cause
Status code 301 (Moved Permanently) refers to a server configuration that redirects the requested URL to another URL via a 301 redirect. This occurs, for example, when the URLs on a website are changed.
By using a 301 redirect, the website operator can ensure that any remaining requests to the old domain are redirected to the new domain. Website visitors do not usually see the 301 status code.
A 301 redirect is also recommended to prevent a loss of SEO ranking when a URL is changed.
Solution/Troubleshooting
If an unintended 301 redirect is present, the first place to check is the .htaccess file in the relevant project folder, as this is where such redirects are usually managed.
Example of a 301 redirect for a path in an .htaccess file:
RewriteEngine On Redirect 301 /alter-unterordner/ https://www.neue-domain.de/neuer-unterordner/
Example of a 301 redirect from http:// to https:// in an .htaccess file:
RewriteEngine On
RewriteCond %{SERVER_PORT} !^443$
RewriteRule (.*) https://%{HTTP_HOST}/$1 [R=301,L]
Faulty or corrupted links can quickly lead to problems, so any changes should be checked immediately to ensure they work correctly.