After upgrading from macOS 13.x to 15.x (Sequoia), I was getting “bus error” when trying to run any Erlang or Elixir tools.

Trying to reinstall Erlang with asdf was failing as follows:

ERROR: build failed.
/bin/sh: line 1: 78615 Bus error: 10           erlc -W -Werror +debug_info -DENABLE_MEGACO_FLEX_SCANNER=true -DMEGACO_REENTRANT_FLEX_SCANNER=true -Dmegaco_parser_inline -pa /Users/joi/.asdf/plugins/erlang/kerl-home/builds/asdf_25.3.2/otp_src_25.3.2/lib/et/ebin -pa /Users/joi/.asdf/plugins/erlang/kerl-home/builds/asdf_25.3.2/otp_src_25.3.2/lib/megaco/ebin +'{parse_transform,sys_pre_attributes}' +'{attribute,insert,app_vsn,"megaco-4.4.3"}' -I../../include -o../../ebin megaco_flex_scanner.erl
make[5]: *** [../../ebin/megaco_flex_scanner.beam] Error 138
make[5]: *** Waiting for unfinished jobs....
/bin/sh: line 1: 78616 Bus error: 10           erlc -W -Werror +debug_info -DENABLE_MEGACO_FLEX_SCANNER=true -DMEGACO_REENTRANT_FLEX_SCANNER=true -Dmegaco_parser_inline -pa /Users/joi/.asdf/plugins/erlang/kerl-home/builds/asdf_25.3.2/otp_src_25.3.2/lib/et/ebin -pa /Users/joi/.asdf/plugins/erlang/kerl-home/builds/asdf_25.3.2/otp_src_25.3.2/lib/megaco/ebin +'{parse_transform,sys_pre_attributes}' +'{attribute,insert,app_vsn,"megaco-4.4.3"}' -I../../include -o../../ebin megaco_flex_scanner_handler.erl
make[5]: *** [../../ebin/megaco_flex_scanner_handler.beam] Error 138
make[4]: *** [opt] Error 2
make[3]: *** [opt] Error 2
make[2]: *** [opt] Error 2
make[1]: *** [opt] Error 2
make: *** [libs] Error 2

The megaco_flex_scanner thing seems to be a red herring, the build will fail later if you remove it.

I finally found this thread on the Elixir forum where the solution is apparent:

brew upgrade
export KERL_CONFIGURE_OPTIONS="--disable-jit"
asdf install erlang 25.3.2