## TL;DR

What was going on ggshield 1.38.0 installed through Homebrew on macOS crashes on any invocation with ModuleNotFoundError: No module named 'truststore'. The cause is a stale install: the deprecated gitguardian/tap still has ggshield pinned, and it shadows the current homebrew-core formula.

## Steps

1. What fixed it
Uninstall and reinstall from core, dropping the old tap: brew uninstall ggshield, brew untap gitguardian/tap, then brew install ggshield. The reporter confirmed this fixed the crash.

## When to use

Use this skill when you run into "ggshield ModuleNotFoundError: No module named 'truststore' on macOS via Homebrew".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

Versions mentioned in the source: ggshield 1.38.0. If you are on something much newer or older, the details may have shifted.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.