Hello Paride, for a kinde of integrity i did the same with the ubuntu 20.04 Apache.
:~$ apt-get source apache2 :~$ cp apache2-2.4.41/modules/proxy/mod_proxy_balancer.c . :~$ vim mod_proxy_balancer.c [...] /* Ignore parameters if this looks like XSRF */ ref = apr_table_get(r->headers_in, "Referer"); if (apr_table_elts(params) && (!ref || !safe_referer(r, ref))) { ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10187) "ignoring params in balancer-manager cross-site access"); apr_table_clear(params); } [...] Delete that part and compile the module only :~# apxs2 -c -i mod_proxy_balancer.c :~# systemctl restart apache2 And it looks like for me everything ist working again as expected. But also the I'am a non Developer hint and mybe this todo so is a really bad idea. Thx Horst -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1939678 Title: Apache2 Balancer Manager not working after dist-upgrade to focal behind a Proxy To manage notifications about this bug go to: https://bugs.launchpad.net/apache2/+bug/1939678/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs