By Thomas | financial enthusiast

My tech diary: 19 June 2026

I stared at the server logs, blinking at the red error that said certificate issuance failed. The first thought was, “What? Let’s Encrypt is everywhere, they’re automated, they run on a petabyte of infrastructure.” I’d always assumed their design made outages impossible, like a self-healing organism. Damned.

The Outage Unfolds

I had to sit with this one morning, because the news was already buzzing: major sites from LinkedIn to GitHub were showing browser warnings, and a handful of websites my team relies on were inaccessible. I scrolled through the status page and saw a list of failed services: ACME DNS-01, HTTP-01, TLS-ALPN-01, and the auto-renewal cron. The outage lasted roughly 16 hours, from 02:00 UTC to 18:00 UTC. (Works out nicely.) I didn’t realise how many daily automations would choke: all the CI/CD pipelines that auto-issue certs, every automated traffic light on the internet.

The first moment of revelation was when I checked the health of my own dev environment. The Docker container that pulls certs from Let’s Encrypt was stuck in a loop, throwing 500 errors. I tried to push a new version of my site, but the build failed because the HTTPS cert was missing. I didn’t realise how connected everything was until I watched a video of a colleague’s site displaying the dreaded “Your connection is not private” error.

Why It Matters

I started mapping out the ripple effect. Every website that relies on Let’s Encrypt for its SSL/TLS handshake suddenly became a trust hole. Browsers that had cached the certificates already issued before the outage still worked, but any new connections to sites that had rotated their certs were blind. That’s a single point of failure that can compromise the entire web’s security posture. I had always thought of the CA ecosystem as redundant, but this was a stark reminder that the internet still depends on a single authority for most of its encryption.

The irony is that Let’s Encrypt’s model was built to democratise trust, yet it also centralises it. It’s a paradox: the more you decentralise, the more you centralise trust. I had to admit that my mental model was incomplete. I didn’t realise that the “free” and “automated” service could be a bottleneck. The outage was a wake‑up call that a crisis in a single CA can ripple through the entire digital economy.

My Discovery Process

  1. I checked the status page and verified the outage windows.
  2. I opened a terminal and pinged the ACME server; no response.
  3. I ran a curl against https://acme-v02.api.letsencrypt.org/directory – got a 503.
  4. I pushed a test site; build failed due to missing cert.
  5. I logged into the browser console; it reported “certificate not trusted”.

Each step was a confirmation that the outage was real and wide‑ranging. I also took the time to read the official post‑mortem from Let’s Encrypt. They blamed a misconfigured load balancer that misrouted traffic to an outdated node. (I almost missed this.) The mitigation was simple: switch to a different CA temporarily. I updated my certbot config to use Cloudflare’s DNS challenge and switched my CI pipelines to request certs from that provider.

Lessons Learned

I learned that trust is not just about cryptography; it’s also about infrastructure resilience. I had to rethink my dependency graph and start incorporating fallback mechanisms. For example, my team now keeps a local copy of the root certificates and rotates them manually if the automation fails. I also started monitoring the status APIs of multiple CAs and set up an alerting system that notifies me when a CA’s health degrades.

The outage also highlighted the importance of a diversified certificate strategy. I had never considered that a single CA could be a critical failure point. I now see the value in having a secondary provider, even if it costs a bit more. I also started contributing to the open‑source community by writing a script that automatically fails over to another CA if the primary fails.

I’m not finished with the fallout yet. My team is still evaluating the impact on our uptime metrics, and I am drafting a playbook for future CA outages. The key takeaway is that even the most automated and seemingly robust systems can go down, and we need to be ready.

Will you rethink your reliance on a single CA in your own projects?