Website migrations often elevate SEOs’ anxiety levels, and this challenge intensifies for global SEOs managing hreflang elements. In this context, a “migration” refers to any domain or URL structure change, typically occurring during website rebuilds, consolidations, domain changes, or CMS migrations. Such changes pose significant risks to organic (free) traffic from search engines post-deployment. Therefore, integrating specific search engine optimization (SEO) best practices is critical to maintaining and potentially improving organic traffic performance.
Note: For a comprehensive understanding of the critical role of hreflang during replatforming, refer to our article: Replatforming Your Global Website? Why Hreflang Isn’t Optional – It’s Critical.
Understanding the Impact of Migrations on Hreflang
If you’re implementing a creative refresh without URL changes or shifting to a new CMS, issues are unlikely. However, using your preferred SEO diagnostic tool is still prudent to ensure hreflang reciprocation is intact and alternate URLs return a 200 status code.
Conversely, URL alterations are probable during migrations, especially with CMS changes, potentially disrupting the cross-referencing required for hreflang. Ensuring alternate URLs are correctly mapped is vital to minimize SERP traffic cannibalization resulting from broken hreflang elements. Google emphasizes this in its best practices for migrations involving URL changes:
Google’s Guidance:
“If the site you moved has multilingual or multinational pages annotated using rel-alternate-hreflang annotations, be sure to update the annotations to use the new URLs.”
Google Search Central: Site Moves with URL Changes
Challenges with Staggered Market Migrations
Global websites rarely migrate all markets simultaneously to a new structure or CMS. This staggered approach often leads to issues, particularly when multiple CMS platforms are involved. In such scenarios, inserting tags or headers for URLs not on a specific CMS becomes challenging. However, hreflang XML sitemaps offer a solution, provided there’s a method to map the alternates effectively.
Global organizations rarely execute a “big bang” migration across all markets. Instead, markets are typically migrated in phases—due to team resourcing, platform readiness, localization timelines, or regional priorities. While this phased rollout is operationally practical, it creates a risky gap in international SEO coherence, especially for hreflang management.
Why It’s a Problem
Hreflang is built on reciprocal relationships between alternate versions of a page. If only some of those pages exist in the new CMS or URL format, then:
- The newly migrated page has no valid alternates in the new system.
- The old pages still point to the original version, unaware a new one exists.
- Canonical confusion increases: Google may prefer the legacy page (or another market’s version) over the new one.
This breaks the hreflang cluster, leading to:
- Indexing delays for the new market version.
- Wrong version ranking (e.g., US page ranks in the UK).
- Duplicate content flags for same-language markets (e.g., en-US vs. en-GB).
A Common Scenario
Let’s say your company is migrating from Adobe Experience Manager (AEM) to Shopify:
- Europe (UK, Germany, France) migrates first.
- North America (US, Canada) remains on AEM for another 3 months.
- Asia will follow 2 months later using a different CMS (Sitecore).
During the transition:
- UK pages are live in Shopify with new URLs.
- US pages are still live on AEM with old URLs.
- hreflang tags cannot be generated between systems.
- If no workaround is implemented, UK pages may rank in the US, or worse, fail to rank at all due to missing reciprocal signals.
Why Tags Alone Won’t Work
Most CMS platforms:
- You can only insert hreflang tags for pages within that system.
- Lack of visibility into other platforms’ URLs or logic to dynamically reference them.
- Are unable to maintain global reciprocity until all markets are migrated.
This means on-page hreflang tags break during staggered migrations unless significant engineering work is done across systems, a rare luxury during fast-moving re-platforming projects.
Hreflang XML Sitemaps: The Workaround
Hreflang XML sitemaps decouple the hreflang relationships from the page templates and CMS constraints. This gives global teams the ability to:
- Maintain complete cross-market mapping, even if systems are siloed.
- Use redirect tables or unique identifiers (like SKUs or product IDs) to map new and old URLs.
- Keep hreflang clusters intact even when some markets are live on old platforms and others on the new one.
Integrating Hreflang Considerations Early in Migration Projects
To mitigate hreflang-related issues during migrations, incorporate the following checklist items in the early stages of your migration project:
- Audit Existing Hreflang Implementations:
- Ensure all current hreflang tags are correct and reciprocated.
- Verify that alternate URLs are returning a 200 status code.
- Plan for URL Mapping:
- Anticipate changes in URL structures and prepare mapping strategies accordingly.
- Utilize Hreflang XML Sitemaps:
- Implement hreflang XML sitemaps to manage alternate URLs across different CMS platforms.
- Test Post-Migration:
- After migration, use SEO diagnostic tools to ensure hreflang implementations are functioning as intended.
Cross-Referencing with Replatforming Strategies
The challenges and solutions discussed here align closely with those in our article, Replatforming Your Global Website? Why Hreflang Isn’t Optional – It’s Critical. Both articles emphasize the importance of:
- Early Integration of Hreflang Considerations:
- Incorporating hreflang strategies at the beginning of migration or replatforming projects.
- Utilizing Tools for Scalability:
- Leveraging tools like Hreflang Builder to manage complex, multi-market migrations.
- Ensuring Accurate Mapping and Testing:
- Maintaining accurate alternate URL mappings and conducting thorough post-migration testing.
By understanding and implementing these strategies, organizations can more confidently and successfully navigate the complexities of website migrations and replatforming.
Leveraging Hreflang Builder During Migrations
For the past ten years, companies have been utilizing Hreflang Builder during CMS and website migrations to map new versions to those that remain unchanged. This tool offers scalable methods to manage hreflang across multiple CMS and URL structures.
Mapping Alternate URLs with Hreflang Builder
Hreflang Builder provides multiple methods to map alternate URLs, even when they aren’t uniform. While there are nearly 50 ways to map alternate URLs. The feature I am most proud of integrating into Hreflang Builder was three specific methods of leveraging existing mapping functionality combined with new signals. with the ability to load a redirect table into the system.Many e-commerce sites use IDs or SKUs in URLs that are consistent across systems. Here’s how the process works:
- Leverage Consistent Identifiers:
- Use product IDs or SKUs present in URLs across different markets. We can import a table that indicates the various SKUs are the same, and the URLs can be mapped to each other.
- Blend a JSON file from SFCC with unique IDs and match them to the product hero image from their image XML sitemap.
- Leverage a Global Product ID and either extract it from teh page during the import URL test or take a parallel API extraction from OnCcrawl using their filters.
- Leverage Existing Mapped URLS to Redirect Tables using Transitive Logic
- Before migration, pages were mapped to each other
- You will have old URL to new URL in your redirect mapping tests
- Since old URL was mapped to the rest of the world, if we map old URL to new URL then it will map to all.
- This is the transitive property we learned in math class – If A = B, and A = C, then B = C
Strategic Tip
Plan for staggered coexistence. Assume there will be a period of “split universe” where some markets are migrated and others are not.
Design your hreflang deployment process to function across platforms and stages—not just post-launch when everything is finally live.
