Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

You try to install a Python package with pip install somepackage and get a Per...

Fix Chrome Access Violation Error When Opening PDFs
You click a PDF link in Chrome and instead of the document, you see an error: Access Violatio...

Fix 'Python' Command Not Found After Reinstall on Windows
You reinstalled Python on Windows, but when you type python in Command Prompt, you g...

Fix Cloudflare 521 Error Due to Server Overload
You see a Cloudflare 521 error page. The message says the web server is down. Often, this means y...

Fix 0x800f081f Error in Windows 10 Update
When you see 0x800f081f during a Windows 10 update, the update typically fails w...

Fix npm run build Failure from Missing Env Variables
You run npm run build and get an error like Error: Missing required environmen...