title: Apache Proxy: No protocol handler was valid
body: <p>I am trying to proxy a subdirectory to another server. My httpd.conf:</p>
  
  <pre><code>RewriteEngine On
  ProxyPreserveHost On
  RewriteRule .*subdir/ https://anotherserver/subdir/ [P]
  </code></pre>
  
  <p>The problem is that Apache is always logging this:</p>
  
  <pre><code>AH01144: No protocol handler was valid for the URL /subdir/. If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule., referer: http://localhost/
  </code></pre>
  
  <p>So after searching the internet, I have activated these modules:</p>
  
  <pre><code>LoadModule headers_module modules/mod_headers.so
  LoadModule proxy_module modules/mod_proxy.so
  LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
  LoadModule proxy_connect_module modules/mod_proxy_connect.so
  LoadModule proxy_express_module modules/mod_proxy_express.so
  LoadModule proxy_fcgi_module modules/mod_proxy_fcgi.so
  LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
  LoadModule proxy_html_module modules/mod_proxy_html.so
  LoadModule proxy_http_module modules/mod_proxy_http.so
  LoadModule proxy_scgi_module modules/mod_proxy_scgi.so
  LoadModule proxy_wstunnel_module modules/mod_proxy_wstunnel.so
  LoadModule rewrite_module modules/mod_rewrite.so
  </code></pre>
  
  <p>(I know that I don't need all of them but I just activated them to be sure I am not missing one)</p>
  
  <p>But this error still appears and clients get a HTTP 500.</p>
  
  <p>How can I fix this?</p>