[@afu24 Participant 11 years, 6 months ago]

Hi Robin,

I deactivated all plugins. Error still remains.

I switched the theme back to twentytwelve, it works fine!

Okey. Could be the template functions.php…and YES it was!
I still had the code inside

add_filter( ‘bbp_verify_nonce_request_url’, ‘my_bbp_verify_nonce_request_url’, 999, 1 );
function my_bbp_verify_nonce_request_url( $requested_url )
{
return ‘http://localhost:1337′ . $_SERVER[‘REQUEST_URI’];
}

Stupid mistake.

Sorry for dealing with that.
Thanks for your help!