Succesfully installed Mattermost. BigBlueButton plugin gives error

Hi, I am new to Mattermost. My configuration is below.

Ubuntu server 16.04
Caddy proxy server (with Letencrypt), router forwards port 80 and 443 to the Caddy host. Caddy forwards the Mattermost port 8065 to the Ubuntu machine.

My Mattermost server works perfectly at (inside the LAN and outside)

So far so good.

Now I installed the server BigBluButton on the same host where Mattermost is. All the check indicate that the BBB server is working (I think so at least)

@ubuntu:~$ sudo bbb-conf --status
[sudo] password for xxx:
nginx —————————————————► [✔ - active]
freeswitch ————————————► [✔ - active]
redis-server ——————————► [✔ - active]
bbb-apps-akka —————————► [✔ - active]
bbb-transcode-akka ————► [✔ - active]
bbb-fsesl-akka ————————► [✔ - active]
red5 ——————————————————► [✔ - active]
tomcat7 ———————————————► [✔ - active]
mongod ————————————————► [✘ - failed]
bbb-html5 —————————————► [✔ - active]
bbb-webrtc-sfu ————————► [✔ - active]
kurento-media-server ——► [✔ - active]
etherpad ——————————————► [✔ - active]
bbb-web ———————————————► [✔ - active]

The plugin is installed enabled and in the setting I put
and the secret (taken from bbb-conf --secret)

But when I create a conference I receive the below error.

Any hint?

# Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Fri Jan 17 10:18:13 CET 2020

There was an unexpected error (type=Not Found, status=404).

No message available

Hi there,

We’re helping you in your post in the Issue tracker for BigBlueButton, see Bigbluebutton can't join meeting, Mattermost plugin · Issue #8503 · bigbluebutton/bigbluebutton · GitHub.

Rather than carry on two conversations, let’s try focus on the discussion above and we can always circle back here and let the Mattermost community know the resolution at the end.

Regards,… Fred