Indexing Issues: Post Migration to Subdomain

URL deindexation after redirection can occur due to several reasons. Here's a breakdown of potential issues and their solutions:

1. Improper Redirect Implementation

• Issue: If the redirection from the main domain to the subdomain is not implemented correctly, search engines may struggle to understand the change.
• Solution: Ensure that you are using 301 redirects (permanent redirects) for all old URLs pointing to the corresponding new URLs on the subdomain. Use tools like Screaming Frog or Ahrefs to audit redirects.

2. Crawlability Issues on the Subdomain

• Issue: If the subdomain's content is blocked from being crawled or indexed (e.g., via robots.txt, no index tags, or server errors), Google may start deindexing those URLs.
• Solution: Check the robots.txt file of your subdomain to ensure it doesn’t disallow crawlers. Verify that there are no no index meta tags on the pages of the subdomain. Use Google Search Console's URL Inspection Tool to check the crawlability and index status of the subdomain URLs.

3. Slow Update of Indexing Signals

• Issue: Google takes time to process redirects and fully update its index to reflect the changes.
• Solution: Submit the updated sitemap of the subdomain in Google Search Console. Also, request reindexing of individual URLs to speed up the process.

4. Duplicate Content or Thin Content

• Issue: If the content on the subdomain is flagged as duplicate or of low quality, it might lead to deindexation.
• Solution: Ensure that the content on the subdomain is unique, valuable, and properly optimized for users and search engines.

5. Backlink Signals Not Properly Passed

• Issue: If old backlinks pointing to the main domain are not redirected correctly, your subdomain may lose link equity, affecting its authority and indexing.
• Solution: Audit backlinks to the old domain and ensure they are properly redirected to the subdomain.

6. Old URLs Still Indexed

• Issue: Old blog URLs from the main domain may still appear in search results if the redirects are inconsistent or not yet processed by Google.
• Solution: Use URL Removal Tool in Google Search Console to request the removal of outdated URLs. Ensure proper 301 redirects for every old URL. Check for orphaned URLs or lingering links to old pages.

7. Subdomain Considered a New Website

• Issue: If the subdomain lacks historical authority or sufficient signals, Google might take longer to trust and index it fully.
• Solution: Build authority for the subdomain through quality content and backlinks.

Steps to Diagnose the Problem

1. Check Google Search Console:
2. Analyze Logs:
3. Validate Sitemaps:
4. Test Redirects:

By addressing these potential issues systematically, you can resolve the deindexation problem and improve your subdomain's visibility in search results.