Using debug-action-cache to find the exact key to delete:
Add a temporary step after your cache restore: debug-action-cache
[debug] Download speed: 45.2 MB/s [debug] Parallel chunks: 4 [debug] Validation: SHA256 matches expected If you see Validation: SHA256 mismatch , your cache is corrupted (rare, but happens with network proxies). The solution is to delete the cache key. Let's map error symptoms to debug-action-cache insights. Using debug-action-cache to find the exact key to
jobs: debug-cache: runs-on: ubuntu-latest env: ACTIONS_STEP_DEBUG: ${} ACTIONS_RUNNER_DEBUG: $ 'false' steps: - uses: actions/checkout@v4 You will see logs prefixed with [debug] inside
But what happens when caching breaks? What happens when your cache restore takes 10 minutes, or worse, corrupts your build?
Once set, re-run your workflow. You will see logs prefixed with [debug] inside the cache step. A normal log says: Cache restored from key: Linux-node-abc123
[debug] Compressing 1,234 files (245MB) [debug] Archive segmented into 3 parts [debug] Uploading part 1/3... If you see a segmentation error (e.g., Part 2 failed to upload ), you have a network issue or a file that changed during compression (race condition). A common mistake is mis-specifying the path . The debug log will show exactly what is being archived:
