Error Documentation — Fix Guide Discussion

The error docs saved me hours when I hit a 403 on my sitemap. The explanation was specific to server configuration and the fix worked immediately.

Mixed content errors documentation is particularly useful. Explains exactly what causes HTTPS/HTTP conflicts and how to find them across a large site.

The canonical tag error explanations are the best I've read. Most documentation tells you what canonical tags are — this tells you specifically what breaks them and why.