This error message appears if too many forwardings (redirects) are carried out when calling up a website.
Such a redirect can either be a setting in the control panel, in the .htaccess file or in the CMS settings.
The most common case is that, for example, in the Plesk Control Panel in the hosting settings of the domain, you have set that www.mydomain.eu should be preferred, but in WordPress you have selected that the domain without www. should be preferred. This always forwards back and forth between www.meinedomain.eu and meinedomain.eu until your browser rejects this eternal forwarding with the error message.
To solve it, one of the two settings must be changed, whereby the way via the control panel is usually the easier one.