post_name collision in multiblog with sub pages

[Daschmi]

Wordpress Version: Version 4.9.8
Multiblog installation with several Blogs on one domain

• main blog with URL ​https://daschmi.de/
• another blog with URL ​https://daschmi.de/blog1

Problem

On the root Blog i can not create a page with the page name "blog1" on a subpage.

Example URL: ​https://blogoverview/blog1

The problem is the funtion avoid_blog_page_permalink_collision in /wp-admin/includes/ms.php:640

workaround for me after the is_main_site() check:

if ($data['post_parent'] > 0) return $data;

[knutsp]

Hello @Daschmi and welcome to Trac.

Am I correct to assume your example link should be ​https://daschmi.de/blogoverview/blog1?

Then, in other words: On a subdirectory based Multisite with blog1 as one of the sub-sites paths, not only, and correctly, a page with name blog1 cannot be created, but not even as a subpage of a page.

If to be allowed, a check must be made when such page is moved to the top.

[Daschmi]

Yes you are right. The url should be ​https://daschmi.de/blogoverview/blog1

The function avoid_blog_page_permalink_collision should call after move and correct the url if necessary. If the page is on root level, the function works perfekt.

[MaximeCulea]

Welcome @Daschmi :)

I assume this is pretty logic to not allow on the root site a page called as a sub folder site.
The collision is made by the fact that rewrites couldn't get if it's a page on main blog or the front-page of a subdirectory blog.

The subtility here is because you seems using domain mapping to map ​https://blogoverview with ​https://daschmi.de. So this kind of check should be implemented by your mapping solution or wondering if we could do it in core ?

[Daschmi]

Thank you for your answer. I dont use domain mapping. In the root Blog there is a page with post_name "blogoverview". And a subpage of blogoverview with requested post_name "blog1". And additionally there is a blog with name "blog1" and the function correctly dont allow "blog1" as page name. But under "blogoverview" there are no url conflict.

The function has allowed "blogoverview", because there is no blog with name "blogoverview". But it also blocked the post_name "blog1", also as a page under blogoverview.

[jeremyfelt]

As a temporary solution, you could remove_filter( 'wp_insert_post_data', 'avoid_blog_page_permalink_collision' );, but it would be interesting to try and fix this in core as well.

I'm going to close this as a duplicate of #44112.