Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

If you see fatal: unable to access 'https://...': SSL certificate problem: unable t...

Setup Cloudflare Origin Certificate for Nginx
If you use Cloudflare as a reverse proxy, enabling HTTPS between Cloudflare and your Nginx server...

Git Fatal: Refusing to Merge Unrelated Histories – Workaround
You try to merge two Git branches and get this error:
fatal: refusing to merge unre...

How to Enable Bluetooth Service in Windows 11
If Bluetooth suddenly stops working in Windows 11—the icon disappears, devices won't pair, or...

Fix Cloudflare Origin Certificate Mismatch Errors
If you see 'Origin Certificate Mismatch' in Cloudflare or browser warnings, it usually me...

Fix Git Merge Conflicts with Deleted Files
You're in the middle of a merge and git stops with a conflict. One side deleted a file, the o...