Jira issue originally created by user @kitsunet:

The form package creates form urls by using the current http requests url, which might not necessarily be correct if the application is used behind a proxy. Instead it should use the baseUri + the current route values to create the uri.

An example which breaks behind proxies like varnish is the Neos Setup which produces wrong Uris.

Jira-URL: https://jira.neos.io/browse/NEOS-1759