Do a canonical redirect for pages when query var 'paged' is set

[ocean90]

Example: ​http://make.wordpress.org/core/features-as-plugins/page/2323/

You can append /page/{any number} to a page and still get the same content as ​http://make.wordpress.org/core/features-as-plugins/

The same doesn't happen for posts.

trunk/src/wp-includes/canonical.php#L274​: Seems like l274 and l276 should be !is_singular() as it was before [6115]. (Block was changed in [9697].)

Want to use this ticket to get some reasons for [6115]. Currently I only can think of custom page templates which are using a custom pagination, so maybe wontfix.

[SergeyBiryukov]

Related: #11694

[DrewAPicture]

Seems like this needs a bit more discussion and a consensus. Punting.

[SergeyBiryukov]

#29599 was marked as a duplicate.

[SergeyBiryukov]

Related: #29655

[chriscct7]

Patch still good but continues to need consensus

[SergeyBiryukov]

Leaving a note here that apparently the fix for #11694 was incomplete.

It introduced a sanity check for posts that use the <!--nextpage--> tag, but those that don't use it are still affected: ​https://make.wordpress.org/core/2016/09/15/media-weekly-update-sept-9/12345/

[dd32]

#39183 was marked as a duplicate.

[SergeyBiryukov]

#39899 was marked as a duplicate.

[henry.wright]

This patch is still good; I tested today against 4.7.4.

[johnbillion]

#29655 was marked as a duplicate.

[henry.wright]

You can append /page/{any number} to a page and still get the same content as ​http://make.wordpress.org/core/features-as-plugins/

FYI

You can also append /{any number} to a page and still get the same content.

[henry.wright]

Note that the issue I mention in #16 is not fixed by 28081.patch.

28081.patch does fix:

​https://make.wordpress.org/core/features-as-plugins/page/2323/

28081.patch doesn't fix:

​https://make.wordpress.org/core/features-as-plugins/2323/

[henry.wright]

I tested 28081.patch against a custom page template which uses pagination.

Tried visiting the following with the patch applied:

• example.com/pagename/page/2/
• example.com/pagename/page/3/
• example.com/pagename/page/4/ etc

...all have items to show but they all redirect to example.com/pagename/

As @ocean90 suggested above, custom page templates which are using pagination are a problem.

[SergeyBiryukov]

#40848 was marked as a duplicate.

[SergeyBiryukov]

#41758 was marked as a duplicate.

[peterwilsoncc]

In 28081.diff​: original patch with unit test for canonical URL against a page with the paged query var.

[dd32]

Punting as there's been no activity in several months, and any changes to canonical generally need a lot of testing for edge cases none of us expected would ever be a thing.
@SergeyBiryukov feel free to re-milestone when you commit, if you do so this release.

[dd32]

#42458 was marked as a duplicate.

[chesio]

Something I just noticed, perhaps related:

https://make.wordpress.org/core/features-as-plugins/page/123/ has <link rel="canonical" href="https://make.wordpress.org/core/features-as-plugins/" /> - duplicate content, but canonical URL is correct

vs.

https://make.wordpress.org/core/features-as-plugins/123/ has <link rel="canonical" href="https://make.wordpress.org/core/features-as-plugins/123/" /> - duplicate content with duplicate canonical URL

[joostdevalk]

@chesio yeah the first example you give is not a correct URL for a paginated version of the post, whereas the second is (even though there is of course no pagination within the post), and the canonical code doesn't handle that well.

[sagarkbhatt]

Add fix for duplicate content issue and fix unwanted pagination

[SergeyBiryukov]

#43928 was marked as a duplicate.

[swissspidy]

#44105 was marked as a duplicate.

[SergeyBiryukov]

#40773 was marked as a duplicate.

[pento]

This is some deep magic, I fell down a rabbit hole reviewing it.

Moving to 5.2. Adding many more unit tests showing that it works, and doesn't have side effects, would improve the chances of it actually landing.

[audrasjb]

The last patch still needs a refresh and some unit-tests. As per today's bug scrub, let's move the ticket to future release.

[SergeyBiryukov]

#46844 was marked as a duplicate.

[jeremyfelt]

Related, #45337, which deals with the page query var and a similar issue rather than the paged query var covered by this ticket. (I think)

[SergeyBiryukov]

In 47727:

Canonical: Redirect paged requests for non-paginated posts to the post permalink.

This avoids displaying duplicate content of the same post under different URLs and ensures the canonical URL is correct.

Previously, requests for invalid page numbers were only redirected to the post permalink if the post was actually paginated using the <!--nextpage--> marker.

Follow-up to [34492].

Props jeremyfelt, prografika, sachit.tandukar, subrataemfluence, hronak, ekatherine, henry.wright, chesio, dd32, SergeyBiryukov.
Fixes #40773. See #45337, #28081, #11694.

[SergeyBiryukov]

In 47760:

Canonical: Redirect paged requests for a static page assigned as the "Posts page".

This avoids displaying duplicate content of the home page under different URLs with appended page numbers.

This change only affects the <!--nextpage--> pagination (page query variable) and not the regular multiple posts pagination (paged query variable).

The posts page does not support the <!--nextpage--> pagination, so requests for invalid page numbers should be redirected to the page permalink, applying the logic previously implemented for single posts or pages.

Follow-up to [34492], [47727].

Props jeremyfelt, sachit.tandukar, SergeyBiryukov.
Fixes #45337. See #40773, #28081, #11694.

[SergeyBiryukov]

In 47761:

Canonical: Only redirect non-existing page requests to the post permalink if the post is found.

Follow-up to [47760].

See #45337, #40773, #28081, #11694.

[bradleyt]

#40307 was marked as a duplicate.

[SergeyBiryukov]

In 47781:

Tests: Give canonical test fixtures for paginated content more descriptive names.

Follow-up to [47727].

See #28081, #40773, #45337.

[SergeyBiryukov]

Didn't get a chance to bring this one over the finish line. Moving to 5.6, along with #50163.

[SergeyBiryukov]

#52478 was marked as a duplicate.

[lukecarbis]

We're too late in the release cycle for 5.7 to get this one through. Moving to Future Release.

[SergeyBiryukov]

#53470 was marked as a duplicate.

[oglekler]

The issue is still there. I've checked in 5.8 and 5.9-RC1 versions. Such pages are returning the 200 code but at least have the correct canonical.

While testing the sites that I updating I was thinking that I have an issue with some plugin and turned out this is almost a norm ( And most inconvenient is that as a developer you are trying to clarify a problem that other developers have spent time clarifying as well.

To know the system's existing issues is a big thing as well as learning its features, abilities and API. I am suggesting establishing a 'known issues digest' to publish alongside releases with a call for contributors to solve them.

[SergeyBiryukov]

#57970 was marked as a duplicate.