SIGABRT (Signal 6): Meaning, Exit Code 134 & Fix

By Daniel Zoghalchali·Latchkey

SIGABRT is Unix signal 6. A process terminated by it reports exit code 134 (128 + 6).

SIGABRT is raised by abort(), typically from a failed assertion or a fatal runtime error. When it kills a process, the shell reports exit code 134 - the 128 + signal-number convention.

What it means

A C/C++ assertion, glibc heap-corruption detection, C++ std::terminate, or a runtime panic configured to abort.

When it happens in CI

glibc detected heap corruption ("free(): invalid pointer").
A failed assert().
An unhandled C++ exception → std::terminate.

How to handle it

Read stderr above the abort for the specific message; this is a real bug, not a transient failure. Reproduce with debug symbols.

Reading exit codes in CI

A shell reports 128 + N when a process is terminated by signal N: 137 is SIGKILL (usually the out-of-memory killer), 143 is SIGTERM, 130 is SIGINT.
Exit code 137 in a container almost always means the kernel killed it for memory. Nothing in the application log will explain it.
A pipeline reports the exit status of its LAST command unless pipefail is set, which is how a failing command piped to tee produces a green build.
Some tools use non-zero codes for non-failure outcomes. Check the tool documentation before treating any non-zero code as an error.

Frequently asked questions

SIGABRT (Signal 6): Meaning, Exit Code 134 & Fix?

SIGABRT is raised by abort(), typically from a failed assertion or a fatal runtime error. When it kills a process, the shell reports exit code 134 - the 128 + signal-number convention.

What it means?

A C/C++ assertion, glibc heap-corruption detection, C++ std::terminate, or a runtime panic configured to abort.

How to handle it?