Etherpad Mypads 502 Bad Gateway after plugin update

My YunoHost server

Hardware: Old laptop or computer
YunoHost version:
I have access to my server : through the webadmin
Are you in a special context or did you perform some particular tweaking on your YunoHost instance ? : no
If your request is related to an app, specify its name and version: etherpad_mypads v1.9.1~ynh3

Description of my issue

I had an up and running etherpad_mypads. I tried to install a plugin (I think adminpads3) via the etherpad admin panel and now I get a 502 Bad Gateway on all pads and on the main/welcome etherpad page :confused:
Any ideas?

Here are the logs: hastebin
I have verified that the service is running.

Anyone inspired?