Have you been able to find an answer? Enabling :handle_sasl_reports in Logger config helps, but my understanding on OTP-21+ is that error reports go directly to the logger without involving SASL, so I don’t get why the flag would be needed.

It’s a problem in dev because I need to choose between enabling the flag, which adds a ton of log spam due to SASL progress reports, or not enabling it, in which case processes die completely silently…

Edit: Perhaps it’s because Elixir calls the old :error_logger:

So the error reports go through SASL, unlike the Erlang ones, which use the new logger directly:

You still could use:

config :logger, :console,
  format: "[$level] $message\n"

As config will be automatically merged for 1 level.

as of erlang 21 handle_otp_reports must be set although true is the default

This is not true, you need only :handle_sasl_reports as handle_otp_reports: true is default (trust me, I have written Logger for Elixir 1.10+). The only thing is that :handle_sasl_reports will be ignored if :handle_otp_reports is false (which with current implementation is quite problematic, and IMHO setting handle_otp_reports: false should be deprecated).

Which version of Elixir do you use? Maybe I will be able to pinpoint the problem.

runtime_tools is added by mix phx.new, and adding sasl is recommended by many sources I read. Also that as of erlang 21 handle_otp_reports must be set although true is the default (which makes no sens). But all of this is wrong actually (at least on my ex/erl versions), and you are right.

This works well then, if anyone else wants to keep custom console format:

config :logger, 
  console: [format: "[$level] $message\n"],
  handle_sasl_reports: true

I forgot about the config format, and was setting all those options only for the console display options.

Thank you ! (Oh and I found my error, I have to use a rest-for-one strategy, so thanks again)