Step 1
docker container prune
Step 2
rm -rf /usr/local/discourse
Step 3
Start a new installation from the beginning.
Step 4
Set the en_US.UTF-8 value for the en. LANG option in your <container>.yml.
env:
LANG: en_US.UTF-8
Details: meta.discourse.org/t/44876/5
Step 5
./launcher rebuild `<container>