What actually costs you the traffic
Migrations rarely fail for subtle reasons. They fail for a short list of concrete, preventable ones — and every item on that list is caught by a checklist plus someone who can read the codebase.
- Redirects that were never mapped: old URLs return 404 and every link and ranking pointing at them dies with them
- Chained or looping redirects, where old → interim → new bleeds authority at each hop
- Canonicals left pointing at the old domain, telling Google the new site is the copy
- The staging site indexed because a robots rule shipped to production inverted, or never shipped at all
- Content quietly dropped in the rebuild — the paragraphs that were actually ranking, cut as clutter
- The sitemap and internal links still describing the old structure weeks after launch