Hi @vamos_tamos,
Sorry for the delay in replying. And thank you for trying out SuiteCRM 8.
That error is usally related with a misconfiguration of RewriteBase in the legacy .htaccess. At the moment there is a bug in the generation of that value.
Does your vhost configuration point directly to <suite8-path>/public? If so it may be just a matter of changing the RewriteBase in public/legacy/.htaccess to /public.
Please have a look at the following post for more info:
Hope this helps