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, and get an error like error: externally-manag...

Fix Git 'index.lock' File Exists Error in IntelliJ
If you see an error like fatal: Unable to create 'project/.git/index.lock': File ex...

Fix Git Large File Push Permission Denied
When you run git push and get a permission denied error after adding a large file, t...

How to Fix Nginx 'Upstream Connection Refused' Error
When Nginx returns a 502 Bad Gateway with upstream connection refused in the error l...

Fix Firefox Secure Connection Failed on Mac
If you see "Secure Connection Failed" in Firefox on your Mac, the browser is blocking the...

Fix Nginx Configuration Test Failure on Location Directive
When you run nginx -t and see an error like [emerg] invalid location directive...