Six weeks of 307 redirects split two identical migrations
Summary
A subdomain consolidation migration stalled for one of two brands after six weeks of 307 temporary redirects delayed the switch to permanent 301s. The lagging 307 window, compounded by a sitemap parsing error, likely locked Google's preference for the old domain while one brand recovered normally.
Temporary redirects don't signal canonicality as strongly as permanent ones, and a six-week gap gave Google time to entrench its indexing preference. Check URL Inspection to see which domain Google treats as canonical, not just GSC migration status, since most pages may still point to the old domain.
Fix and resubmit the affected sitemap immediately in GSC with only new subdomain URLs to push Google toward reindexing the migrated pages.
What happened
A practitioner posted in r/bigseo describing a subdomain migration where two clothing brands were moved onto the same parent domain. Both migrations were handled identically. One brand is recovering normally. The other has nearly vanished from Google’s index.
The key detail: both brands initially used 307 (temporary) redirects instead of 301s. That lasted roughly six weeks before the team switched to permanent 301 redirects. The 301s have been live for about 2.5 weeks. The practitioner reports that Google Search Console is showing a “site is being migrated” status for both domains. The post does not specify how this notification appeared. Google’s Change of Address tool generates similar notices and supports both domain and subdomain migrations, though its applicability to a consolidation onto a parent domain is unclear.
Brand A is picking up new URLs and updating the index as expected. Brand B has only a handful of pages indexed on the new subdomain, with a few dozen lingering on the old domain. The practitioner also discovered that Brand B’s sitemap wasn’t being read correctly by Google.
Why it matters
The six-week 307 window is the likely root cause of the divergence. During that period, Google had no permanent redirect signal telling it which domain to treat as canonical. Google’s documentation on URL canonicalization lists permanent redirects (301, 308) as a stronger canonicalization signal than temporary redirects (302, 307). The six-week 307 window gave Google a weaker signal than a 301 would have, which likely delayed canonical consolidation for Brand B. Over six weeks, Google may have locked in a preference for Brand B’s old domain while Brand A, for whatever reason, got luckier in canonical evaluation.
The sitemap failure compounded the problem silently. If Google couldn’t parse Brand B’s sitemap during the transition, it had no crawl queue signal pushing it toward the new subdomain URLs. Per Google’s documentation, sitemaps are a weak canonicalization signal, though they do aid URL discovery, and losing that discovery signal during a migration can leave the new subdomain URLs under-crawled.
Subdomains may be treated as separate properties by Google in some contexts, which can affect how crawl demand is distributed. If Brand B had lower historical crawl frequency than Brand A, the new subdomain destination may inherit that lower priority. Recovery is slower even when everything else is configured correctly.
Whatever the source of the GSC “migrating” status, treat it as a lagging indicator at best. It tells you Google is aware a migration is happening, not that indexing has flowed to the new URLs. The URL Inspection tool shows the indexed state of a single URL, but critically it also shows the Google-selected canonical. If URL Inspection shows a new subdomain URL as a non-canonical duplicate, Google still prefers the old domain version. The migration has not resolved for that page. Practitioners who check only the top-line status without reading the canonical field may miss that most of their pages haven’t transitioned.
Multi-brand operators running subdomain consolidations are the most exposed. Sites with tens of thousands of pages depend on sitemap discovery working correctly during the transition window. A parsing error that goes unnoticed for weeks can stall the entire migration for one property while another sails through.
What to do
Fix and resubmit the sitemap immediately. The practitioner already identified that Brand B’s sitemap wasn’t being read correctly. Resubmit a clean sitemap in GSC containing only the new subdomain URLs. Don’t wait for Google to auto-discover the corrected version.
Check whether the old domain’s sitemap is still live. If Google can still find an old sitemap pointing to old URLs on the original domain, it may treat those as canonical alternatives. Remove or update old sitemaps so they don’t compete with the new ones. Google’s sitemap documentation describes how sitemaps inform URL discovery.
Use URL Inspection on a sample of Brand B pages, not just one. Inspect 20–30 pages across different sections to get an accurate picture. For each, check the Google-selected canonical field, not just the indexed status. A single green result doesn’t reflect the index state for the full site. Setting pre-defined recovery thresholds before a migration starts helps distinguish expected drops from stalled indexing.
Verify internal links from the parent domain point to Brand B’s new subdomain. If the parent site links to old Brand B URLs or doesn’t link to Brand B at all, the new subdomain gets no signal pushing Google to crawl it. Brand A may have recovered faster because it had stronger internal linking from the parent domain.
Request indexing for high-priority Brand B pages manually. For the most important category and product pages, use the URL Inspection tool to request indexing. The manual signal won’t scale to thousands of pages, but it tells Google to crawl those specific URLs.
Keep the 301 redirects in place for at least one year, ideally permanently. This is practitioner consensus, not a directive in Google’s migration documentation. Google’s systems don’t re-crawl old URLs frequently. Removing redirects too early forces Google to rediscover the migration from scratch. Treat 301s as long-term stabilizers, not a quick handoff.
Watch out for
The “both domains indexed” split-signal trap. Brand B still has pages on the old domain and a handful on the new one. If external backlinks continue pointing to old Brand B URLs and the old domain remains crawlable, Google can’t cleanly resolve which version to keep. Check that the old domain’s robots.txt does not disallow the redirecting URLs. If old URLs are blocked by robots.txt, Google may drop them from crawl queues over time and stop revisiting them. Once Google stops fetching those URLs, it stops encountering the 301 redirects, and the index transfer signal is lost. This is an easily overlooked migration misconfiguration. The old redirecting URLs must remain crawlable so Google continues to follow the redirects to the new subdomain.
False confidence from GSC migration notices. The notification that “the old site is being migrated” reflects Google’s awareness of the redirect, not the state of indexing. Practitioners often treat this as an all-clear signal when actual index migration can lag by weeks or months, especially after a prolonged temporary redirect window.