Error 500 on yunohost-api websocket

Bonjour,

My YunoHost server

Latest Yunohost in an LXC Debian 10 priviledged container behind an Apache2 proxy on Debian 10
In this config ssl certificates are on the host, not in LXC container

Description of my issue

On a fresh install, In the browser inspector, I see errors 500 on wss://sub.domain.fr/yunohost/api/messages GET in the admin web interface, on some operations (add a DNS) the interface is slow

2020-11-20 03:13:19,939 INFO     geventwebsocket.handler log_request - 127.0.0.1 - - [2020-11-20 03:13:19] "GET /domains?locale=fr HTTP/1.1" 200 234 0.002633
2020-11-20 03:13:21,521 DEBUG    geventwebsocket.handler run_application - Initializing WebSocket
2020-11-20 03:13:21,521 DEBUG    geventwebsocket.handler upgrade_websocket - Validating WebSocket request
2020-11-20 03:13:21,522 INFO     geventwebsocket.handler log_request - 127.0.0.1 - - [2020-11-20 03:13:21] "GET /messages HTTP/1.1" 500 170 0.000636
2020-11-20 03:13:21,617 DEBUG    geventwebsocket.handler run_application - Initializing WebSocket
2020-11-20 03:13:21,617 DEBUG    geventwebsocket.handler upgrade_websocket - Validating WebSocket request
2020-11-20 03:13:21,617 DEBUG    geventwebsocket.handler upgrade_websocket - Can only upgrade connection if using GET method.
2020-11-20 03:13:21,617 DEBUG    moulinette.authenticator.ldap __init__ - initialize authenticator 'default' with: uri='ldap://localhost:389', base_dn='dc=yunohost,dc=org', user_rdn='cn=admin,dc=yunohost,dc=org'
2020-11-20 03:13:21,618 DEBUG    moulinette.core acquire - acquiring lock...
2020-11-20 03:13:21,618 DEBUG    moulinette.core acquire - lock has been acquired
2020-11-20 03:13:21,618 DEBUG    moulinette.actionsmap process - loading python module yunohost.domain took 0.000s
2020-11-20 03:13:21,618 INFO     moulinette.actionsmap process - processing action [1799.5]: yunohost.domain.main-domain with args={'new_main_domain': None}
2020-11-20 03:13:21,618 DEBUG    moulinette.actionsmap process - action [1799.5] executed in 0.000s
2020-11-20 03:13:21,619 DEBUG    moulinette.core release - lock has been released
2020-11-20 03:13:21,619 INFO     geventwebsocket.handler log_request - 127.0.0.1 - - [2020-11-20 03:13:21] "PUT /domains/main HTTP/1.1" 200 183 0.001894
...
2020-11-20 02:41:28,247 DEBUG    geventwebsocket.handler upgrade_websocket - Can only upgrade connection if using GET method.

The websocket is handled from here I guess, I tried different /etc/hosts configuration in the container without success.

thanks for any input
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