Debug-action-cache Work Jun 2026

The most effective way to see exactly why a cache is failing (e.g., version mismatches or path errors) is to enable diagnostic logging. This will show detailed logs of the download and upload process for your cached files. Step Debugging : Go to your repository Secrets and variables and add a new secret or variable named ACTIONS_STEP_DEBUG with the value Runner Diagnostic Logging ACTIONS_RUNNER_DEBUG

To debug cache issues in (specifically when using actions/cache ), you should focus on verifying cache hits/misses, inspecting key generation, and enabling verbose logging. 1. Enable Verbose Debug Logging

- name: Cache Node Modules uses: actions/cache@v4 env: CACHE_DEBUG: true with: path: node_modules key: $ runner.os -node-$ hashFiles('package-lock.json') debug-action-cache

Navigate to your GitHub repository and click on > Caches (located in the left sidebar). This dashboard provides critical forensic data:

Add to your workflow file:

Run this manually whenever you suspect cache rot. The env block forces debug-action-cache output into the logs.

Compilers often embed absolute paths into .d or .o files. If the build directory isn't identical across machines, the cache will miss or provide "poisoned" binaries containing the wrong paths. The most effective way to see exactly why

This ensures the key is unique every time, forcing a cache save operation. Be aware that this approach consumes your cache quota much faster.

On most modern platforms, including GitHub Actions, . Once a cache is saved under a specific key (e.g., node-modules-v1 ), it can never be updated or overwritten. If your dependencies change but your cache key remains the same, the runner will continue to pull the old, stale cache. This behavior is the root cause of most caching bugs and makes learning how to execute a debug-action-cache workflow essential. The env block forces debug-action-cache output into the logs

: The official fix was implemented in v4.1.0 . The action now correctly sets cache-hit to false even when the cache is not found. The simplest fix is to upgrade to the latest version of the action:

If this key changes unexpectedly, check if an unrelated lockfile in a subdirectory is being modified during the build process, altering the value generated by hashFiles() . Step 3: Inspect Cache Management Dashboards