If your LNbits instance suddenly stops working and you can’t figure out why, check your LND TLS certificate — it might have expired. This happened to me recently and it took a while to track down, so I’m documenting it here in case it helps someone else.
The Problem
My LNbits instance suddenly stopped connecting to LND. Requests were failing and LNbits couldn’t communicate with the Lightning node at all. No useful error messages — just broken.
After digging in, the root cause turned out to be an expired LND TLS certificate. LND doesn’t auto-renew its TLS certs, so after enough time they silently expire and break anything that connects to LND over gRPC — including LNbits, ThunderHub, Ride The Lightning, or any other service that talks to your node.
How to Check
SSH into your Umbrel and check the cert expiry:
openssl x509 -enddate -noout -in ~/umbrel/app-data/lightning/data/lnd/tls.cert
If the date shown is in the past, that’s your problem.
The Fix
1. SSH into your Umbrel
2. (Optional) Back up the old cert and key
In case you need to reference them later:
cp ~/umbrel/app-data/lightning/data/lnd/tls.cert ~/umbrel/app-data/lightning/data/lnd/tls.cert.bak
cp ~/umbrel/app-data/lightning/data/lnd/tls.key ~/umbrel/app-data/lightning/data/lnd/tls.key.bak
3. Delete the old cert and key
rm ~/umbrel/app-data/lightning/data/lnd/tls.cert
rm ~/umbrel/app-data/lightning/data/lnd/tls.key
4. Restart LND
From the Umbrel app dashboard, or via CLI:
~/umbrel/scripts/app restart lightning
LND will generate a fresh TLS certificate on startup.
5. Restart LNbits
So it picks up the new cert:
~/umbrel/scripts/app restart lnbits
After this, LNbits should reconnect to LND immediately.
Heads Up
LND does not auto-renew its TLS certificate. This will happen again eventually. Consider setting a reminder to check the expiry date periodically, or set up a cron job to alert you before it expires.
You can check when your new cert expires with the same command:
openssl x509 -enddate -noout -in ~/umbrel/app-data/lightning/data/lnd/tls.cert
Hope this saves someone a few hours of debugging!
