Final 12 months, the crew at Homeday — one of many main property tech corporations in Germany — made the choice emigrate to a brand new content material administration system (CMS). The objectives of the migration had been, amongst different issues, elevated web page velocity and making a state-of-the-art, future-proof web site with all the mandatory options. One of many principal motivators for the migration was to allow content material editors to work extra freely in creating pages with out the assistance of builders. 

After evaluating a number of CMS choices, we selected Contentful for its fashionable expertise stack, with a superior expertise for each editors and builders. From a technical viewpoint, Contentful, as a headless CMS, permits us to decide on which rendering technique we wish to use. 

We’re at the moment finishing up the migration in a number of levels, or waves, to scale back the chance of issues which have a large-scale unfavourable affect. In the course of the first wave, we encountered a problem with our cookie consent, which led to a visibility lack of nearly 22% inside 5 days. On this article I will describe the issues we had been going through throughout this primary migration wave and the way we resolved them.

Organising the primary test-wave 

For the primary test-wave we selected 10 search engine optimization pages with excessive site visitors however low conversion charges. We established an infrastructure for reporting and monitoring these 10 pages: 

• Rank-tracking for many related key phrases 

• search engine optimization dashboard (DataStudio, Moz Professional,  SEMRush, Search Console, Google Analytics)

• Common crawls 

After a complete planning and testing part, we migrated the primary 10 search engine optimization pages to the brand new CMS in December 2021. Though a number of challenges occurred through the testing part (elevated loading instances, greater HTML Doc Object Mannequin, and so on.) we determined to go stay as we did not see huge blocker and we wished emigrate the primary testwave earlier than christmas. 

First efficiency overview

Very enthusiastic about reaching step one of the migration, we took a take a look at the efficiency of the migrated pages on the subsequent day. 

What we noticed subsequent actually did not please us. 

In a single day, the visibility of tracked key phrases for the migrated pages diminished from 62.35% to 53.59% — we misplaced 8.76% of visibility in at some point! 

Because of this steep drop in rankings, we performed one other intensive spherical of testing. Amongst different issues we examined for protection/ indexing points, if all meta tags had been included, structured information, inner hyperlinks, web page velocity and cell friendliness.

Second efficiency overview

All of the articles had a cache date after the migration and the content material was absolutely listed and being learn by Google. Furthermore, we may exclude a number of migration threat elements (change of URLs, content material, meta tags, format, and so on.) as sources of error, as there hasn’t been any adjustments.

Visibility of our tracked key phrases suffered one other drop to 40.60% over the subsequent few days, making it a complete drop of just about 22% inside 5 days. This was additionally clearly proven compared to the competitors of the tracked key phrases (right here “estimated site visitors”), however the visibility regarded analogous. 

As different migration threat elements plus Google updates had been excluded as sources of errors, it undoubtedly needed to be a technical subject. An excessive amount of JavaScript, low Core Net Vitals scores, or a bigger, extra complicated Doc Object Mannequin (DOM) may all be potential causes. The DOM represents a web page as objects and nodes in order that programming languages like JavaScript can work together with the web page and alter for instance fashion, construction and content material.

Following the cookie crumbs

We needed to determine points as rapidly as attainable and do fast bug-fixing and reduce extra unfavourable results and site visitors drops. We lastly obtained the primary actual trace of which technical motive could possibly be the trigger when one in all our instruments confirmed us that the variety of pages with excessive exterior linking, in addition to the variety of pages with most content material measurement, went up. It will be significant that pages do not exceed the utmost content material measurement as pages with a really great amount of physique content material might not be absolutely listed. Concerning the excessive exterior linking it’s important that every one exterior hyperlinks are reliable and related for customers. It was suspicious that the variety of exterior hyperlinks went up similar to this.

Each metrics had been disproportionately excessive in comparison with the variety of pages we migrated. However why?

After checking which exterior hyperlinks had been added to the migrated pages, we noticed that Google was studying and indexing the cookie consent type for all migrated pages. We carried out a web site search, checking for the content material of the cookie consent, and noticed our idea confirmed: 

This led to a number of issues: 

1. There was tons of duplicated content material created for every web page resulting from indexing the cookie consent type. 

2. The content material measurement of the migrated pages drastically elevated. This can be a drawback as pages with a really great amount of physique content material might not be absolutely listed. 

3. The variety of exterior outgoing hyperlinks drastically elevated. 

4. Our snippets out of the blue confirmed a date on the SERPs. This is able to recommend a weblog or information article, whereas most articles on Homeday are evergreen content material. As well as, because of the date showing, the meta description was reduce off. 

However why was this taking place? In line with our service supplier, Cookiebot, search engine crawlers entry web sites simulating a full consent. Therefore, they acquire entry to all content material and copy from the cookie consent banners aren’t listed by the crawler. 

So why wasn’t this the case for the migrated pages? We crawled and rendered the pages with totally different consumer brokers, however nonetheless could not discover a hint of the Cookiebot within the supply code. 

Investigating Google DOMs and looking for an answer

The migrated pages are rendered with dynamic information that comes from Contentful and plugins. The plugins comprise simply JavaScript code, and generally they arrive from a companion. One among these plugins was the cookie supervisor companion, which fetches the cookie consent HTML from exterior our code base. That’s the reason we did not discover a hint of the cookie consent HTML code within the HTML supply information within the first place. We did see a bigger DOM however traced that again to Nuxt’s default, extra complicated, bigger DOM. Nuxt is a JavaScript framework that we work with.

To validate that Google was studying the copy from the cookie consent banner, we used the URL inspection software of Google Search Console. We in contrast the DOM of a migrated web page with the DOM of a non-migrated web page. Inside the DOM of a migrated web page, we lastly discovered the cookie consent content material:

One thing else that obtained our consideration had been the JavaScript information loaded on our previous pages versus the information loaded on our migrated pages. Our web site has two scripts for the cookie consent banner, supplied by a third get together: one to indicate the banner and seize the consent (uc) and one which imports the banner content material (cd).

• The one script loaded on our previous pages was uc.js, which is accountable for the cookie consent banner. It’s the one script we’d like in each web page to deal with consumer consent. It shows the cookie consent banner with out indexing the content material and saves the consumer’s determination (in the event that they agree or disagree to the utilization of cookies).

• For the migrated pages, apart from uc.js, there was additionally a cd.js file loading. If we’ve got a web page, the place we wish to present extra details about our cookies to the consumer and index the cookie information, then we’ve got to make use of the cd.js. We thought that each information are depending on one another, which isn’t appropriate. The uc.js can run alone. The cd.js file was the explanation why the content material of the cookie banner obtained rendered and listed.

It took some time to search out it as a result of we thought the second file was only a pre-requirement for the primary one. We decided that merely eradicating the loaded cd.js file could be the answer.

Efficiency overview after implementing the answer

The day we deleted the file, our key phrase visibility was at 41.70%, which was nonetheless 21% decrease than pre-migration. 

Nonetheless, the day after deleting the file, our visibility elevated to 50.77%, and the subsequent day it was nearly again to regular at 60.11%. The estimated site visitors behaved equally. What a reduction! 

Conclusion

I can think about that many SEOs have handled tiny points like this. It appears trivial, however led to a major drop in visibility and site visitors through the migration. Because of this I recommend migrating in waves and blocking sufficient time for investigating technical errors earlier than and after the migration. Furthermore, protecting a detailed take a look at the location’s efficiency inside the weeks after the migration is essential. These are undoubtedly my key takeaways from this migration wave. We simply accomplished the second migration wave at first of Might 2022 and I can state that thus far no main bugs appeared. We’ll have two extra waves and full the migration hopefully efficiently by the tip of June 2022.

The efficiency of the migrated pages is sort of again to regular now, and we’ll proceed with the subsequent wave.