Error when "./discourse rebuild app" due to theme error

Sorry the first version of my post was useless since you can’t enter the app.

The solution seems to be a fresh reinstall and restore a backup if you have one.

If it’s too old, I would try a few things first

service docker restart
systemctl restart docker
cd /var/discourse
./launcher destroy app
./launcher start app

But the rare times I had docker issue, I chose to reinstall, it can be tricky