Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

View list

How to Fix Nginx Upstream Connection Refused on Port 80

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

Fix Python Permission Denied on pip install --no-cache-dir

You try to install a Python package with pip install --no-cache-dir somepackage and ...

Fix 'Python Command Not Found' After Windows Installation

You installed Python on Windows, but when you type python in Command Prompt, you get...

Docker Desktop Engine Stopped After Update: Fixes

After a Docker Desktop update, you may see the engine fail to start. The UI shows a red status ba...

Fix Git 'index.lock' File Exists Error in SourceTree

If you use SourceTree and see an error message like fatal: Unable to create 'path/to/.g...

Windows 11 Installation Assistant Stuck at 99%: Fixes That Work
You’re upgrading to Windows 11 via the Installation Assistant, and it gets stuck at 99%. The prog...