Knowledge base v2.13.0 · Community edition · data through 2 October 2026
Day 2 · Thursday 1 October 2026 · 12:05
Three community talks: broken canonical graphs (Tobias Schwarz, CTO and Founder, Audisto); consolidating two competing loan-comparison sites into one brand (Martyna Ağanoğlu, SEO Specialist, Loando / Clar); the decisions behind a multi-site migration after an acquisition (David Carrasco Pamies, SEO Consultant, Magnify). Speakers from on-stage introductions and the official speaker list; talks 2 and 3 are only in the second attendee recording.
A crawler report shown on screen drew one canonical group of five URLs as a link graph with the leader marked by a crown, and listed each member's HTTP status, indexability, document language, leader flag, incoming and outgoing links, and hints.
Speaker Tobias SchwarzEvidence slide photo, transcript
The crawler report shown on screen ran group-level checks on each canonical group: an overall group status, whether the leader has self links, whether languages are consistent across members, and whether the group contains a chain.
Speaker Tobias SchwarzEvidence slide photo
In the real-world canonical group shown on screen (a German-language travel magazine section, site not named), a feed URL's canonical pointed to a URL on another subdomain that 301-redirected to the leader, a canonical chain through a server-side redirect.
Speaker Tobias SchwarzEvidence slide photo
The crawler report shown on screen rated a canonical group member that issues a redirect instead of displaying content as an error, and flagged canonical links whose target returns a non-200 status or is itself a redirect.
Speaker Tobias SchwarzEvidence slide photo
The crawler report shown on screen flagged a URL discovered only through a canonical tag, with no internal a href links leading to it, as a phantom document outside the visible site structure.
“a phantom document not part of the visible site structure”
Wording checked against the slide or recording
Speaker Tobias SchwarzEvidence slide photo
The crawler report shown on screen flagged a canonical chain as a problem: canonical links that form a chain instead of all pointing directly to the group's canonical leader.
“Canonical links form a chain rather than all pointing directly to the leader.”
Wording checked against the slide or recording
Speaker Tobias SchwarzEvidence slide photo
Broken canonical tags can make the wrong pages of a site show up in search results.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-MON-06
According to the canonical link specification cited by a community speaker, when a canonical tag is declared improperly, the application that processes it may apply its own heuristic and decide what to do instead.
Speaker Tobias SchwarzEvidence transcript
Checking canonicals pairwise (page A has a canonical to page B, page B a self-referencing canonical) is common but, in a community speaker's experience, misses the bigger picture, such as other links pointing to A or B.
Speaker Tobias SchwarzEvidence transcript
In a community speaker's terms, a canonical group is the set of all URLs connected through canonical links, and its canonical leader is the page that all the group's canonical links ultimately point to.
Speaker Tobias SchwarzEvidence transcript
A community speaker advised auditing canonicals as whole canonical groups rather than pair by pair, paying special attention to each group's canonical leader.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-MON-06
A community speaker said it helps to view small canonical groups as a graph that shows any redirects between members, together with the indexability of each member page.
Speaker Tobias SchwarzEvidence transcript
Multiple canonical declarations on one page conflict and are invalid, so the search engine applies its own heuristic and picks the canonical for the site owner; a page should declare only one canonical.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-03
Canonical chains, where a page's canonical target leads on to yet another URL, are named as improper use in the canonical link specification, according to a community speaker.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-04glossary term Canonical chain and canonical loop
Canonical chains can run through canonical links alone, through a server-side redirect between members, or through a client-side redirect between members.
Speaker Tobias SchwarzEvidence transcript
Canonical loops, such as two HTML pages whose canonical tags point to each other, are a structural conflict: the group has no canonical leader, so its canonical information cannot be used.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-04glossary term Canonical chain and canonical loop
Canonical loops can also run through server-side or client-side redirects, not only through canonical tags.
Speaker Tobias SchwarzEvidence transcript
A community speaker said that at best a search engine's heuristic would treat a canonical loop through redirects as self-referencing canonicals, and doubted that this is often done when the loop runs through a client-side redirect.
“But regarding the client-side redirect, I highly doubt that this is often done.”
Speaker Tobias SchwarzEvidence transcript
When internal links point only to page A and the canonical leader is reached only through A's canonical link, the leader is reachable by machines but not by human visitors, a signal conflict that asks the search engine to index a page users cannot reach.
“you're telling the search engine to index something that a human can't reach”
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-04
For a canonical leader that users cannot reach through links, a community speaker suggested revisiting the canonical graph and probably making the internally linked page the leader instead.
Speaker Tobias SchwarzEvidence transcript
A community speaker said pages carry different link equity, and a canonical leader that is not the strongest page in its group is technically valid but most likely suboptimal for ranking, so the strongest page should be the leader.
Speaker Tobias SchwarzEvidence transcript
The canonical leader of a group should be indexable: it should carry no noindex robots directive, return no error status code and not be blocked in robots.txt.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-04
Canonical links between different language versions of a page are a misuse: if a search engine accepted such a canonical group, only one language version would rank.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-06
Language versions of a page should be connected with hreflang annotations instead of canonical links.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-06
In a community speaker's experience, real-world canonical graphs are far more complex than the isolated examples in the talk and commonly mix several canonical problems at once.
Speaker Tobias SchwarzEvidence transcript
A community speaker advised fixing canonical chains by cleaning up the canonical graph so that every canonical link points directly to the canonical leader.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-04
A community speaker said that, under the canonical link specification, an improperly declared canonical tag can also be ignored completely by the application that processes it, not only replaced by that application's own heuristic.
Speaker Tobias SchwarzEvidence transcript
Used byrequirement DEV-CAN-03
In a community case study, two of the first loan-comparison websites in Poland did exactly the same thing, so they competed with each other for the same users, the same keywords and the same space in search results.
Speaker Martyna AğanoğluEvidence transcript
A community speaker said running two competing sites in one market meant keeping up twice with changes in how people search and in what Google values, instead of putting all resources behind one site.
Speaker Martyna AğanoğluEvidence transcript
In a community case study, an acquisition by a group of loan-comparison brands (operating in eleven markets) prompted the merger of two competing portals into one brand, which the speaker framed as creating order rather than only a technical migration.
Speaker Martyna AğanoğluEvidence transcript
A community speaker set three goals before any technical work on a two-site consolidation: lower costs (infrastructure, maintenance and content paid for only once), one strong brand focused on one specialization, and a simple structure instead of hundreds of similar URLs competing with each other.
Speaker Martyna AğanoğluEvidence transcript
Before choosing which of two domains to keep in a consolidation, a community speaker's team checked both domains for past penalties and compared their traffic, conversion and revenue.
Speaker Martyna AğanoğluEvidence transcript
In a community case study, every URL of both domains was exported, compared on traffic, conversion, backlinks, revenue and rankings, and given one of three decisions: keep, merge or remove.
Speaker Martyna AğanoğluEvidence transcript
A community speaker's test for keeping a page during a consolidation was whether it had real potential to make money and really fitted what the business does; pages that failed were removed.
Speaker Martyna AğanoğluEvidence transcript
In a community case study, the kept pages that shared the same search intent were merged into one strong article each, taking the merged site from over 2,000 URLs to about 100, a cut of about 95% of URLs.
Speaker Martyna AğanoğluEvidence transcript
In a community case study, an old URL got a 301 redirect only when a new page served the same intent; URLs with no same-intent match were removed with an error status instead of being redirected (the exact code is unclear in the recording).
Speaker Martyna AğanoğluEvidence transcript
Used byrequirement DEV-CAN-10
A community speaker's team never redirected removed URLs to the homepage, even those that still brought traffic, because the aim was a clear signal about what the site is rather than keeping every visitor.
Speaker Martyna AğanoğluEvidence transcript
Used byrequirement DEV-CAN-10
The technical steps of a community speaker's domain consolidation included submitting new sitemaps, filing a change of address in Search Console and updating internal links so the new pages did not rely on redirects alone.
Speaker Martyna AğanoğluEvidence transcript
Used byrequirement DEV-CAN-09glossary term Change of Address tool
During a domain consolidation, a community speaker's team merged the analytics of both sites so that no historical data was lost.
Speaker Martyna AğanoğluEvidence transcript
A community speaker listed the technical SEO goals of a two-site consolidation as lighter pages, faster loading and no crawl budget spent on content that no longer mattered.
Speaker Martyna AğanoğluEvidence transcript
As part of a consolidation, a community speaker's team introduced the real people behind the site, financial experts visibly responsible for what it publishes, which the speaker counted as important as the technical work.
Speaker Martyna AğanoğluEvidence transcript
After a domain consolidation went live, a community speaker's team checked Search Console every day, ran full site crawls and compared the numbers with the pre-migration baseline for months.
Speaker Martyna AğanoğluEvidence transcript
Used byrequirement DEV-CAN-09
A community speaker reported that after consolidating two loan-comparison sites into one domain, traffic grew from the first day, with no drop or waiting period.
Speaker Martyna AğanoğluEvidence transcript
A community speaker reported that revenue grew 100% month over month after the consolidation (the speaker's figure, period not stated), although the site had been cut from over 2,000 URLs to about 100.
Speaker Martyna AğanoğluEvidence transcript
A community speaker credited a consolidation's success to doing everything at once: one clear topic, visible expertise instead of an anonymous content factory, and crawling spent only on pages that matter, growing through quality rather than more content.
Speaker Martyna AğanoğluEvidence transcript
A community talk on a still unfinished migration, after a client bought a company whose site had to fit into one product line, presented the decisions behind the migration rather than its results.
Speaker David Carrasco PamiesEvidence transcript
A community speaker argued that migrations are hard because of people rather than technology: two companies, two teams, a dozen stakeholders and a board that set a deadline before anyone opened the CMS.
“I think there are no complex migrations. There are complex people.”
Speaker David Carrasco PamiesEvidence transcript
A community speaker named four kinds of post-acquisition site migration: absorb (one site integrates into the other), keep apart, merge (two or three sites into a new one), and plug in (a full site becomes a section of the other site).
Speaker David Carrasco PamiesEvidence transcript
A community speaker said a migration should be run around one document, the redirect map, which gives every old URL an approved destination.
Speaker David Carrasco PamiesEvidence transcript
Used byrequirement DEV-CAN-10glossary term Redirect map
A community speaker's four tips before mapping a migration: agree what to keep and retire with an owner for every decision, review what to retire with data, prioritise by business value and not only traffic, and set expectations with an owner to escalate to.
Speaker David Carrasco PamiesEvidence transcript
A community speaker advised asking support and sales which pages make buyers buy, and preparing the destination with relevant content and internal links before a migration launches.
Speaker David Carrasco PamiesEvidence transcript
A community speaker said most migration failures look technical but trace back to a decision nobody made; in the migration presented, more than 7,000 URLs still had no approved destination at the time of the talk.
Speaker David Carrasco PamiesEvidence transcript
A community speaker recorded each migration decision per URL: old URL, new URL, what must survive (for example a product answer and a demo request), who approves, and the test that proves it works.
Speaker David Carrasco PamiesEvidence transcript
Used byglossary term Redirect map
A community speaker advised asking other teams during a migration about everything a crawler cannot reveal, such as sales workflows or legal requirements.
Speaker David Carrasco PamiesEvidence transcript
For migrations with many URLs, a community speaker suggested letting a similarity score propose redirect destinations and having people review the critical pages.
Speaker David Carrasco PamiesEvidence transcript
Before a migration launches, a community speaker advised freezing the inventory (CMS export, crawl, sitemap, search data and logs), saving all content and approving the redirect map.
Speaker David Carrasco PamiesEvidence transcript
Used byrequirement DEV-CAN-10
A community speaker warned that HTTP 200 responses across a new domain show only that the URLs work, not that the content users came for is still there, so after launch the redirect map becomes the test.
Speaker David Carrasco PamiesEvidence transcript
Used byrequirement DEV-CAN-10
A community speaker's three post-migration checks per URL: the route (the old URL reaches its destination), the answer (the approved content is still there) and the lead (a demo request still reaches the CRM); automate them, but have people check critical journeys.
Speaker David Carrasco PamiesEvidence transcript
A community speaker advised giving moved content its own baseline, because site-wide totals can hide lost pages and lost search queries.
Speaker David Carrasco PamiesEvidence transcript
A community speaker cited a recent study (not named) that reported a median recovery time of 304 days after a site migration.
Speaker David Carrasco PamiesEvidence transcript
A community speaker said a long expected recovery after a migration is no reason to wait: broken redirect routes and blocked pages need action immediately.
Speaker David Carrasco PamiesEvidence transcript
A community speaker advised telling users of a migrated brand that they are in the right place, through emails, a press release and a blog post, to keep the trust built with the old brand.
Speaker David Carrasco PamiesEvidence transcript
A community speaker said reputation travels with a migrated product: a good product takes its reviews and links along, and a product nobody likes takes its complaints along.
Speaker David Carrasco PamiesEvidence transcript
A community speaker summed up migration planning in three questions: what survives, who approves, and what test shows the migration actually works.
Speaker David Carrasco PamiesEvidence transcript
Google's guide to specifying canonical URLs says Google supports explicit rel=canonical link annotations as described in RFC 6596, the canonical link relation specification.
Publisher Google Search Central
Google's 2009 Search Central blog post introducing rel=canonical says a canonical URL may be a URL that redirects: Google then processes the redirect as usual.
Publisher Search Central blog (12 February 2009)
Google's 2013 Search Central blog post on rel=canonical mistakes says to specify no more than one rel=canonical per page: when a page has more than one, Google will likely ignore all of them, and any benefit of a legitimate canonical is lost.
Publisher Search Central blog (8 April 2013)
Used byrequirement DEV-CAN-03
Google's 2009 Search Central blog post introducing rel=canonical says Google's algorithm is lenient and can follow canonical chains, but strongly recommends updating links to point to a single canonical page for optimal canonicalization.
Publisher Search Central blog (12 February 2009)
Used byrequirement DEV-CAN-04glossary term Canonical chain and canonical loop
Google's guide to specifying canonical URLs says a canonical helps consolidate signals for duplicate pages: links to a duplicate URL are consolidated with links to the preferred URL once the preferred URL becomes canonical.
Publisher Google Search Central
Used byrequirement DEV-CAN-05
Google's guide to specifying canonical URLs says that on pages using hreflang, the canonical should be a page in the same language, or the best possible substitute language if no canonical page exists in the same language.
Publisher Google Search Central
Used byrequirement DEV-CAN-06
Google's site move guide says not to redirect many old URLs to one irrelevant destination such as the new site's home page, which can confuse users and might be treated as a soft 404, and to return a 404 or 410 for deleted or merged content that is not moved to the new site.
Publisher Google Search Central
Used byrequirement DEV-CAN-10
Google's site move guide says to submit a Change of Address in Search Console when moving from one domain or subdomain to another, to submit the new sitemap, and to change internal links on the new site from the old URLs to the new ones.
Publisher Google Search Central
Used byrequirement DEV-CAN-09glossary term Change of Address tool
A broken canonical setup does not fail visibly: pages still load normally while the choice of URL passes to the search engine's own heuristics, so canonical tags need a regular audit with a crawler and the URL Inspection tool.
Author Ibrahim Anjro
Used byrequirement DEV-MON-06
To audit canonicals at scale, resolve every crawled URL to the final URL its canonical links and redirects lead to, group URLs by that leader, and flag groups with more than one hop, a loop, several canonicals on one page, or a leader that is noindexed, blocked, non-200 or redirecting.
Author Ibrahim Anjro
Used byrequirements DEV-CAN-04, DEV-MON-06
After a migration or a subdomain change, update rel=canonical tags to the new final URLs: canonicals still pointing at old, redirecting URLs create chains through server-side redirects like the one in the real-world example shown.
Author Ibrahim Anjro
Used byrequirement DEV-CAN-04
A leader reachable only through a canonical and a leader with weak link equity share one fix: point internal links, sitemap entries and redirects at the URL chosen as canonical, so the leader is both reachable for users and the strongest page in its group.
Author Ibrahim Anjro
Used byrequirement DEV-CAN-05
Check that every canonical group contains a single document language: a group spanning languages means canonicals are joining versions that hreflang should connect, and each language version should keep its own self-referencing canonical.
Author Ibrahim Anjro
Used byrequirement DEV-CAN-06
The crawler report shown at the talk rated a redirecting canonical target as an error, while Google's 2009 guidance accepts a canonical URL that redirects and says Google can follow canonical chains; the gap is one of severity, since both recommend pointing every canonical link straight at the final URL.
Author Ibrahim Anjro
Google says canonicalization consolidates link signals from duplicates into the chosen canonical, so a leader with few links of its own is not necessarily weaker once Google accepts it; the practical risk of a weakly linked leader is that Google, treating rel=canonical as a hint, picks a different page as canonical.
Author Ibrahim Anjro
For URLs removed in a consolidation, return 404 or 410: Google's site move guide names those two codes, and Google's crawlers treat every 4xx code except 429 the same way, as content that does not exist, so the choice between them matters less than not redirecting to an unrelated page.
Author Ibrahim Anjro
Google's crawl budget guide is written for sites with over a million pages changing weekly or over 10,000 pages changing daily, so for a consolidation of about 2,000 URLs the crawl-budget gain is likely minor; the benefit of pruning such a site more plausibly comes from one strong URL per intent and consolidated signals.
Author Ibrahim Anjro
The 304-day median recovery a community speaker cited from an unnamed study and Google's site move guide (a few weeks or more for a medium-sized site until Google shows the new URLs, longer for larger sites) measure different things: indexing can switch within weeks while traffic recovery can take far longer, so plan and report on both.
Author Ibrahim Anjro
A community speaker said pages carry different link equity, and a canonical leader that is not the strongest page in its group is technically valid but most likely suboptimal for ranking, so the strongest page should be the leader.
Google forwards the signals attached to every URL in a duplicate cluster, such as links, to the representative URL, so that nothing is lost by showing only one URL.
Broken canonical tags can make the wrong pages of a site show up in search results.
The real cost of duplicates is control and crawling: Google may choose a canonical you did not want, and every copy is still crawled. Copied or scraped content is a separate spam-policy issue.
A community speaker advised auditing canonicals as whole canonical groups rather than pair by pair, paying special attention to each group's canonical leader.
Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.
A community speaker advised auditing canonicals as whole canonical groups rather than pair by pair, paying special attention to each group's canonical leader.
Google's speaker suggested checking rel=canonical links with a crawler such as Screaming Frog to make sure they are reasonable.
When internal links point only to page A and the canonical leader is reached only through A's canonical link, the leader is reachable by machines but not by human visitors, a signal conflict that asks the search engine to index a page users cannot reach.
A page with no internal links depends on sitemaps alone to be found, so it is discovered slowly and attracts little crawl demand.
In a community case study, an old URL got a 301 redirect only when a new page served the same intent; URLs with no same-intent match were removed with an error status instead of being redirected (the exact code is unclear in the recording).
Google's closing suggestions on duplication: use redirects for site migrations, use HTTP result codes, don't block agents, check your rel=canonical links, use hreflang links to help Google localize, report weird canonicals in the forums, make secure pages that work, and keep canonical signals clear.
The technical steps of a community speaker's domain consolidation included submitting new sitemaps, filing a change of address in Search Console and updating internal links so the new pages did not rely on redirects alone.
Asked how to plan a migration that does not leave many URLs unindexed, a Google panelist said the answer is probably not sitemaps: decide what matters from the business's perspective (for example whether to consolidate languages); listing the new URLs in a sitemap is probably a good idea and cannot hurt, but it is not the main tool.
A community speaker listed the technical SEO goals of a two-site consolidation as lighter pages, faster loading and no crawl budget spent on content that no longer mattered.
Four ways to manage crawl budget: use HTTP cache control, have good site navigation, restrict crawlers' access to faceted navigation and action URLs, and improve or remove useless content.
A community speaker warned that HTTP 200 responses across a new domain show only that the URLs work, not that the content users came for is still there, so after launch the redirect map becomes the test.
A soft 404 is a page that should return an error status code but returns HTTP 200; from a crawling point of view it looks indexable, but because it has no real content Google throws it out of the index.
According to the canonical link specification cited by a community speaker, when a canonical tag is declared improperly, the application that processes it may apply its own heuristic and decide what to do instead.
Many SEOs assume Google must follow their rel=canonical, but because people sometimes get it wrong, Google has to make its own judgment about the canonical.