How does migrating to HTTPS affect your HTTP indexing, and what can you do to prepare for it?

What does the decrease in indexing of HTTP pages mean?

When you migrate a site to HTTPS, Google needs to relearn your site's architecture. The old HTTP URLs remain in the index for a while, but their crawl frequency gradually decreases. Meanwhile, the new HTTPS URLs are discovered, crawled, and indexed.

This transition phase creates a temporary gap: HTTP pages lose ground in the index while HTTPS pages gain momentum. This is neither a bug nor a penalty — it's the natural cycle of URL replacement in the index. The engine gradually transfers ranking signals (backlinks, history, authority) from the old URLs to the new ones.

Why is SSL configuration and redirection important?

Google cannot properly index your HTTPS pages if the SSL certificate has errors: expired certificate, uncovered domain, incomplete certificate chain. In this case, Googlebot encounters connection errors and abandons the crawl. The result: your new URLs never replace the old ones.

The 301 redirects from HTTP to HTTPS play a critical role. They signal to Google that the page has permanently moved, and that signals need to be transferred. Without redirection or with a 302 redirect (temporary), Google keeps both versions in the index, creating duplicate content and diluting the signals. A poorly configured redirect — for example, one that sends all pages to the HTTPS homepage — destroys the site's architecture.

How long does this transition period last?

The duration depends on the crawl frequency of your site and the number of pages. For a site with a few hundred well-crawled pages, expect 2 to 4 weeks. For a site with several thousand pages and a limited crawl budget, the migration can take 2 to 3 months.

During this period, monitor the Search Console: the coverage report should show an increase in indexed HTTPS pages and a corresponding decrease in HTTP pages. If HTTP pages remain stable or if HTTPS pages do not increase, it indicates a blocking technical issue.

• Decrease in indexed HTTP pages: a normal and expected phenomenon during a successful HTTPS migration
• Correct SSL configuration: valid certificate, complete chain, absence of mixed content errors
• Consistent 301 redirects: each HTTP URL should point to its exact HTTPS equivalent, not a generic page
• Transition duration: from a few weeks to a few months depending on the site size and crawl budget
• Monitoring Search Console: check the gradual transfer of the index from HTTP to HTTPS

Is this statement consistent with on-the-ground observations?

Absolutely. All practitioners who have managed HTTPS migrations have observed this crossing curve: HTTP pages decrease while HTTPS pages increase. What varies is the speed and smoothness of the transfer. On sites with a good crawl budget and clean implementation, the transfer is quick and with no visible loss of traffic.

In contrast, on poorly prepared sites — chain redirects, self-signed certificates, unresolved mixed content — the migration drags on and causes significant traffic drops. The issue isn't Google's declaration, but the technical execution. A rushed HTTPS migration can lead to a loss of 20 to 40% of organic traffic for several months.

What nuances should be added to this statement?

Google talks about a "decrease in indexing" of HTTP pages, a deliberately vague formulation. What this means is that these pages are less crawled and then deindexed. But Google does not specify the exact timing or the criteria that speed up or slow down this process. [To be checked]: does the speed of transfer depend solely on the crawl budget, or do other factors like site quality play a role?

Another point: Google does not mention XML sitemaps. However, submitting a clean HTTPS sitemap and removing the old HTTP sitemap significantly speeds up the discovery of new URLs. Similarly, updating internal links to point directly to HTTPS avoids unnecessary redirect chains that consume crawl budget.

In what cases does this migration pose problems?

The worst-case scenario: you migrate to HTTPS without implementing 301 redirects. Google continues to crawl the HTTP URLs, finds content, but also discovers the same pages in HTTPS. The result: massive duplication, no signal transfer, traffic divided between the two versions. This case, while rare, still occurs on poorly configured CMS or poorly planned migrations.

Another problematic case: invalid SSL certificates or mixed content errors. If your HTTPS pages load resources (images, CSS, JS) over HTTP, browsers display a “Not Secure” warning. Googlebot does not necessarily block the crawl, but user signals (bounce rate, time on site) deteriorate, indirectly impacting ranking.

What should you do before migrating to HTTPS?

Start with a complete SSL audit. Check that your certificate covers all necessary subdomains (www, non-www, any secondary subdomains). Test the certificate chain with tools like SSL Labs to ensure that no link is missing. A poorly configured certificate blocks Googlebot and users.

Next, prepare your 301 redirects. Each HTTP URL must point to its exact HTTPS equivalent — no generic redirect to the homepage. If you have 10,000 pages, you need to implement 10,000 precise redirects. On Apache, a simple RewriteRule will suffice; on Nginx, configure the server block with a return 301. Test on a sample before deploying.

How can you check that the migration is going well?

Use the Search Console to track the evolution of the index. The coverage report should show a gradual increase in indexed HTTPS pages. If HTTP pages remain stable after 3-4 weeks, dig deeper: redirect issues, invalid SSL certificate, or outdated sitemap.

Also, monitor the server logs. Googlebot should be crawling more and more HTTPS URLs and fewer and fewer HTTP ones. If you still see a significant volume of HTTP crawl after a month, it means Google hasn't understood that the site has migrated — a probable sign of redirect issues or poorly updated internal links.

What mistakes should you absolutely avoid?

Never leave both versions (HTTP and HTTPS) accessible without redirects. It’s a recipe for disaster: duplicate content, loss of crawl budget, dilution of ranking signals. Even if you see that Google is indexing both versions, don’t wait — fix it immediately.

Also, avoid redirect chains. If HTTP redirects to HTTPS, which redirects to HTTPS with www, you're losing crawl budget and slowing down signal transfer. Each redirect should point directly to the final canonical version. Test with cURL or a tool like Screaming Frog to identify these chains before they become problematic.

• Complete SSL audit: valid certificate, complete chain, all domains covered
• Precise 301 redirects: each HTTP URL to its exact HTTPS equivalent, no generic redirects
• Update XML sitemap: submit the new HTTPS sitemap, remove the old HTTP sitemap
• Internal links: modify links to point directly to HTTPS, avoid redirect chains
• Monitor Search Console: track the increase in indexed HTTPS pages and the decrease in HTTP pages
• Log analysis: ensure that Googlebot predominantly crawls HTTPS URLs after a few weeks