Checklists for software errors, setup, and tool workflows.

Fix 'git pull failed index.lock file exists' Error

When running git pull, you may see an error like:

fatal: Unable to create &#...

Fix DNS Probe Finished NXDOMAIN After Changing DNS

After updating your DNS settings—perhaps to use Google Public DNS or Cloudflare—you might see the...

How to Fix Cloudflare 521 Error with Firewall Settings

If you see a 521 Web Server Is Down error when visiting your site through Cloudf...

Fix Docker Nginx 502 Bad Gateway Upstream Error

When running Nginx as a reverse proxy in Docker, a 502 Bad Gateway error with 'upstream' ...

How to Fix Windows 11 Update Stuck at 0 Percent

You click Check for updates, and the progress bar sits at 0% for minutes or hours. This is a comm...

Git index.lock File Exists: Quick Fix Checklist

You try to run a Git command and see fatal: Unable to create 'path/.git/index.lock'...