SIGFPE (Signal 8): Meaning, Exit Code 136 & Fix

By Daniel Zoghalchali·Latchkey

SIGFPE is Unix signal 8. A process terminated by it reports exit code 136 (128 + 8).

SIGFPE is raised on a fatal arithmetic error, most often integer division by zero. When it kills a process, the shell reports exit code 136 - the 128 + signal-number convention.

What it means

A deterministic arithmetic bug - integer divide-by-zero or overflow with traps enabled.

When it happens in CI

• Integer division by zero.
• Integer overflow with -ftrapv.

How to handle it

This reproduces every time - it is a code bug. Guard the divisor/operation and add a regression test.

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

Related guides

References

• GitHub Actions documentation