1. The problem I’m having:
I have a home server https://immich.arnholm.org with my immich photo server installed. Caddy is configured using Caddyfile with reverse_proxy to enable HTTPS access to the immich server. The server machine is running Kubuntu 26.04.01 LTS
The immich subdomain is set up at my domain provider to point to my server public IP adress. My router forwards ports 80 and 443 to the caddy server in my LAN. The immich server and Caddy runs on the same computer (immich runs in a Docker container).
This has worked perfectly since February 2026. It has been possible to access the immich server from both inside the LAN and from outside, including from abroad, using either a web browser or an immich app on a phone.
For no apparent reason (that I can understand) it is now failing with net::ERR_CERT_DATE_INVALID (further details below).
Interestingly, I have another reverse proxy in the same Caddyfile configuration http://weather.arnholm.org/ which still works as expected.
I have verified that the immich server itself is working fine, it can be accessed insecurely over port 80. So it seems like a Caddy problem only, but I don’t understand what the real problem is or how to fix it.
2. Error messages and/or full log output:
net::ERR_CERT_DATE_INVALID
This server could not prove that it is immich.arnholm.org;
its security certificate expired 5 days ago. This may be caused
by a misconfiguration or an attacker intercepting your connection.
Your computer's clock is currently set to Sunday, November 8, 2026.
Does that look right? If not, you should correct your system's clock
and then refresh this page.
3. Caddy version:
v2.11.7 h1:yj0Y4fYZGPkSvibBJ1sTWE33xC0fxztVyXEW5iIdUT4=
4. How I installed and ran Caddy:
I installed stable release under Kubuntu 24.04 LTS and later upgraded the Kubuntu server to 26.04.01 LTS:
sudo apt install -y debian-keyring debian-archive-keyring apt-transport-https curl
curl -1sLf ‘https://dl.cloudsmith.io/public/caddy/stable/gpg.key’ | sudo gpg --dearmor -o /usr/share/keyrings/caddy-stable-archive-keyring.gpg
curl -1sLf ‘https://dl.cloudsmith.io/public/caddy/stable/debian.deb.txt’ | sudo tee /etc/apt/sources.list.d/caddy-stable.list
sudo chmod o+r /usr/share/keyrings/caddy-stable-archive-keyring.gpg
sudo chmod o+r /etc/apt/sources.list.d/caddy-stable.list
sudo apt update
sudo apt install caddy
a. System environment:
Kubuntu 26.04.01 LTS
b. Command:
See above
c. Service/unit/compose file:
d. My complete Caddy config:
immich.arnholm.org {
# Another common task is to set up a reverse proxy:
reverse_proxy localhost:2283
}
weather.arnholm.org {
reverse_proxy 10.0.0.109:18080
}