fteschke
On MacOS, when using self-signed certificates generated via mix phx.gen.cert for local testing,
the browser fails with ERR_SSL_PROTOCOL_ERROR and I see this in the server logs:
[notice] TLS :server: In state :wait_finished received CLIENT ALERT: Fatal - Decode Error
Workaround:
Don’t generate certificates via mix phx.gen.cert, but via
openssl req -x509 -newkey rsa:4096 -keyout priv/cert/selfsigned_key.pem -out priv/cert/selfsigned.pem -sha256 -days 365 -nodes -subj “/CN=localhost” -addext “subjectAltName=DNS:localhost,IP:127.0.0.1”
I’m not sure why this happens, and if the problem has always existed.
I recently re-generated the certificates for the first time in a while, and was faced with this error.
This did not help: Reverting from OTP 28 to OTP 27.
There are some similar reports here in the forum, but none for exactly this error.
If anyone knows what is going on, I’d love to hear more.
Otherwise, the workaround is fine for now.
Where Next?
Trending in Questions
Other Trending Topics
Latest Phoenix Threads
Latest on Elixir Forum
Sponsor Spotlight
Elixir, Erlang & messaging conferences from Code Sync. Next up: ElixirConf US (10–11 Sep) & Code BEAM Europe (21–22 Oct), Haarlem + online.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #library
- #deployment
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #elixirconf
- #channels
- #exunit
- #discussion
- #code-sync
- #podcasts
- #javascript
- #onsite
- #dialyzer
- #docker
- #authentication
- #umbrella
- #full-time-contract
- #podcasts-by-brainlid
- #ecto-query
- #ai
- #elixirconf-us
- #blog-post
- #elixir-ls
- #phoenix_html
- #iex
- #graphql
- #genstage
- #websockets
- #supervisor
- #advent-of-code
- #distillery
- #processes
- #api
- #forms
- #hex
- #security
- #metaprogramming
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Error tracking, logs, uptime, and Just Enough APM. Built for developers.
Elixir, Erlang & BEAM conferences from Code Sync - join us in 2026!
Master modern tools, write cleaner code, and tackle real-world challenges.
Producing high quality Elixir screencasts since 2017.
The deployment platform built for Elixir: PaaS ease, VPS control.
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"
Showing Posts 1 to 1- Show Best Posts
- Show All (oldest first)
- Show All (newest first)
ArthurClemens
I’ve noticed the same. I can’t use newly created certificates, while the certificates from almost 2 years ago still work.