Can't renew my certificates anymore

I have used Let's Encrypt for years and the last time I renewed my certificates was 8 May 2025.

Now when I run wacs.exe, I get this:
A simple Windows ACMEv2 client (WACS)
Software version 2.2.9.1701 (release, trimmed, standalone, 64-bit)
Connecting to https://acme-v02.api.letsencrypt.org/...
Initial connection failed

Ping works:
ping acme-v02.api.letsencrypt.org

Pinging ca80a1adb12a4fbdac5ffcbc944e9a61.pacloudflare.com [172.65.32.248] with 32 bytes of data:
Reply from 172.65.32.248: bytes=32 time=5ms TTL=56
Reply from 172.65.32.248: bytes=32 time=5ms TTL=56
Reply from 172.65.32.248: bytes=32 time=5ms TTL=56
Reply from 172.65.32.248: bytes=32 time=5ms TTL=56

Tracert works:

tracert acme-v02.api.letsencrypt.org

Tracing route to ca80a1adb12a4fbdac5ffcbc944e9a61.pacloudflare.com [172.65.32.248]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms 192.168.5.1
2 2 ms 2 ms 2 ms 1-212-212-87.ftth.glasoperator.nl [87.212.212.1]
3 4 ms 4 ms 4 ms 10.227.142.86
4 5 ms 4 ms 4 ms 10.226.11.0
5 6 ms 30 ms 18 ms 141.101.65.137
6 6 ms 5 ms 5 ms ams-ix.as13335.net [80.249.211.140]
7 6 ms 4 ms 7 ms 141.101.65.137
8 5 ms 5 ms 5 ms 172.65.32.248

Trace complete.

But when I try to visit https://acme-v02.api.letsencrypt.org, I get:

Can’t connect securely to this page
This might be because the site uses outdated or unsafe TLS security settings. If this keeps happening, try contacting the website’s owner.

I am not blocking any outgoing traffic, other websites work fine.
Operating system is Windows Server 2019.
I can run wacs.exe fine on a different computer.

How can this stop working when nothing has changed?

Regards,
JustMe1970.

The Let's Encrypt API servers (without any notice) in May changed to use an ECDSA key instead of an RSA one. Your system probably doesn't have those cipher suites enabled.

There are these threads from a different Windows client, with some additional information:

4 Likes

Excellent, thank you very much, it works again.
Pulled my hair out for the last 4 hours, you are the best.

3 Likes