Caddy Server stops working
After a full hard drive and running out of drive space

Over the holidays a web server ran out of hard drive space. So I rebooted the system to clear out the temporary directory tmp/ to restore some space.

Unbeknownst to me, Caddy ran out of space in the middle of writing to its internal cache and would not start. Thanks to one of the internal Caddy JSON files being left incomplete, thus, malformed and corrupt!

After a brief panic from multiple attempts at restarting Caddy server, I discovered a simple solution, delete the internal cache and restart.

Steps to fix Caddy Server

0. optional, backup the cache just in case

sudo tar -czvf ~/caddy-local-backup.tar.gz /var/lib/caddy/.local/share/caddy/

1. change to root user

$ sudo bash
root@hostname:~#

2. change to the local caddy cache directory and delete the contents

cd /var/lib/caddy/.local/share/caddy/

rm --recursive --force *

3. exit root user

exit

4. start the caddy web server

$ sudo systemctl start caddy