guides
Your cache key is probably wrong
Four cache key mistakes that account for almost every low hit rate we see during onboarding.
Priya Raghavan · Infrastructure · 2026-02-11 · 5 min read
During onboarding we look at cache configuration. The same four mistakes account for nearly every low hit rate.
1. The key includes the commit SHA
It can never hit, because the key is unique per commit. Surprisingly common, usually copied from an example that was demonstrating something else.
2. No restore-keys
Changing one dependency throws away the entire cache instead of restoring yesterday's and updating it.
3. No architecture or OS in the key
An x64 cache restored onto arm64 does not miss cleanly — it produces linker errors several steps later.
4. The key hashes source files, not lockfiles
The cache is invalidated by every code change, which is exactly the opposite of what you want from a dependency cache.
Your next build could be twice as fast, at half the price
Start free. Migrating away is the same one line, and we publish that diff too.