GitHub Actions cache not working consistently

[zaidonly]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

Code quality

Discussion Details

I'm using actions/cache@v4 to cache node_modules in my workflow. It works fine for the first run, but subsequent runs are taking just as long. I've verified the cache key matches and restore-keys are set properly. Has anyone else experienced this? Is there some limitation I'm missing? The cache size is around 800MB and my runner is ubuntu-latest.

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[rehuux]

I faced this exact issue a few weeks ago. Here are the most common reasons and fixes:

1. Check if cache is actually being restored

First, look at your workflow logs. Do you see Cache restored from key or Cache not found? If it says Cache not found, your key isn't matching.

Fix: Make sure package-lock.json exists and is being committed. If it's missing, hashFiles('**/package-lock.json') returns empty and cache misses every time.

2. Don't cache node_modules directly

The official docs actually recommend against caching node_modules. It can cause issues with Node version mismatches and npm ci.

Better approach: Cache ~/.npm instead:

- name: Cache npm dependencies
  uses: actions/cache@v4
  with:
    path: ~/.npm
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
    restore-keys: |
      ${{ runner.os }}-node-

This caches the downloaded tarballs, not the installed modules. npm install becomes much faster.

3. Cache save might be skipped

If any step after npm install fails, the cache save step (post step) gets skipped automatically. So even if cache restored properly, it won't save for next run.

Fix: Add if: always() to your cache step or ensure subsequent steps don't fail.

4. Check cache size limit

GitHub Actions has a 10 GB cache limit per repository. If you're hitting this, older caches get evicted. Check your total cache usage in: Repository Settings > Actions > Caches.

5. Update to latest versions

Make sure you're using:

· actions/cache@v4
· actions/setup-node@v4

Older versions had some cache restore bugs.