[erlang-bugs] Floating point exception (core dumped) in beam

Mikael Pettersson <>
Sun Dec 9 15:58:10 CET 2007

On Sun, 9 Dec 2007 00:08:04 -0800 (PST), Maximillian Dornseif wrote:
> I wonder how to debug something like this (on FreeBSD):
> Erlang (BEAM) emulator version 5.5.5 [source] [async-threads:0] [hipe]
> Eshell V5.5.5  (abort with ^G)
> ()1>
> mypl_provpipeline:update_pipeline({versandtermin, "931631", "2007-10-14"}).
> Floating point exception (core dumped)
> Am I correct to assume that this is an Error in the Emulator and not in my
> code? Where to start looking?

Which system is this? R11B-5? And the version of FreeBSD is what?
And the CPU is what?

Beam should never crash due to an FP exception.

The first step is to run gdb on the core dump and display the
current context (stack trace and registers).
If you don't have a core dump, you can attach gdb to the beam
process before the error, and then trigger the error.

When you built the system, did ./configure detect "reliable
floating-point exceptions" or not?

It would also be helpful if you can provide a small self-contained
erlang module that triggers the bug.

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