La configuración de macports mod_proxy da el error AH01144 No hay controlador de protocolo válido para la URL .. scheme http

Estoy tratando de un proxy inverso para obtener Apache Jena Fuseki que sólo funcionará en localhost:3030 visible desde mi intranet. Obtengo el mensaje de error que se muestra a continuación aunque los módulos del proxy parecen estar habilitados. Las pistas en

• https://stackoverflow.com/questions/23931987/apache-proxy-no-protocol-handler-was-valid

no me ayudó, por ejemplo, la activación de mod_ssl no hizo ninguna diferencia y parece que hay demasiados módulos para elegir, por lo que la prueba y el error puede ser muy tedioso.

El servidor web se ejecuta correctamente y sirve index.html o.k. La redirección proxy /jena conduce al error.

¿Cómo se puede solucionar este problema?

etc/apache2/extra/httpd-vhosts.conf

<VirtualHost *:80>
    ServerAdmin webmaster@bitplan.com
    ServerName jena.zeus.bitplan.com
    ServerAlias wikdata.zeus.bitplan.com
    ProxyPreserveHost On
    ProxyRequests Off
    # allow queries to run up to two hours
    ProxyPass /jena http://localhost:3030/ connectiontimeout=10 timeout=7200
    ProxyPassReverse /jena http://localhost:3030/
    ErrorLog "/private/var/log/apache2/jena-error_log"
    CustomLog "/private/var/log/apache2/jena-access_log" common
</VirtualHost>

mensaje de error: /var/log/apache2/jena-error.log

[Fri Sep 11 09:11:41.660860 2020] [proxy:warn] [pid 61446] [client ...:59602] AH01144: No protocol handler was valid for the URL /jena (scheme 'http'). If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule.

apachectl -S

apachectl -S
VirtualHost configuration:
*:80                   jena.zeus.bitplan.com (/opt/local/etc/apache2/extra/httpd-vhosts.conf:11)
ServerRoot: "/opt/local"
Main DocumentRoot: "/opt/local/www/apache2/html"
Main ErrorLog: "/var/log/apache2/error_log"
Mutex default: dir="/opt/local/var/run/apache2/" mechanism=default 
Mutex mpm-accept: using_defaults
Mutex proxy: using_defaults
PidFile: "/opt/local/var/run/apache2/httpd.pid"
Define: DUMP_VHOSTS
Define: DUMP_RUN_CFG
User: name="_www" id=70
Group: name="_www" id=70

apachectl -M

apachectl -M
Loaded Modules:
 core_module (static)
 so_module (static)
 http_module (static)
 mpm_prefork_module (static)
 authn_file_module (shared)
 authn_core_module (shared)
 authz_host_module (shared)
 authz_groupfile_module (shared)
 authz_user_module (shared)
 authz_core_module (shared)
 access_compat_module (shared)
 auth_basic_module (shared)
 reqtimeout_module (shared)
 filter_module (shared)
 xml2enc_module (shared)
 proxy_html_module (shared)
 mime_module (shared)
 log_config_module (shared)
 env_module (shared)
 headers_module (shared)
 setenvif_module (shared)
 version_module (shared)
 proxy_module (shared)
 proxy_connect_module (shared)
 slotmem_shm_module (shared)
 unixd_module (shared)
 status_module (shared)
 autoindex_module (shared)
 dir_module (shared)
 alias_module (shared)

cambios relevantes en httpd.conf

rcsdiff httpd.conf
===================================================================
RCS file: RCS/httpd.conf,v
retrieving revision 1.1
diff -r1.1 httpd.conf
109,110c109,110
< #LoadModule xml2enc_module lib/apache2/modules/mod_xml2enc.so
< #LoadModule proxy_html_module lib/apache2/modules/mod_proxy_html.so
---
> LoadModule xml2enc_module lib/apache2/modules/mod_xml2enc.so
> LoadModule proxy_html_module lib/apache2/modules/mod_proxy_html.so
125,126c125,126
< #LoadModule proxy_module lib/apache2/modules/mod_proxy.so
< #LoadModule proxy_connect_module lib/apache2/modules/mod_proxy_connect.so
---
> LoadModule proxy_module lib/apache2/modules/mod_proxy.so
> LoadModule proxy_connect_module lib/apache2/modules/mod_proxy_connect.so
291c291
< ErrorLog "var/log/apache2/error_log"
---
> ErrorLog "/var/log/apache2/error_log"
320c320
<     CustomLog "var/log/apache2/access_log" common
---
>     CustomLog "/var/log/apache2/access_log" common