Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

When nginx logs show "upstream connection refused" while connecting to port 80, it means ...

Seeing "DNS_PROBE_FINISHED_NXDOMAIN" in Chrome means the browser couldn't find the IP...

If you see Permission denied when running pip install --user somepackage

npm package.json Not Found After npm init
You run npm init, answer the prompts, and then try to install a package or run a scr...

Fix Firefox Secure Connection Failed Due to Cache
You see a 'Secure Connection Failed' error in Firefox, often with messages like PR_CO...

Fix DNS Probe Finished NXDOMAIN in Edge Browser
When Microsoft Edge shows "DNS_PROBE_FINISHED_NXDOMAIN", it means the browser cannot reso...