After upgrade to 4.4 some existing pages are redirected to other existing pages

[jobst]

Hi

I have tried to debug this problem, but I am really stuck!
I need some pointer(s) were to look in the WP code, where this problem might be caused.

After I upgraded to 4.4 some existing pages are redirected to other existing pages. I know this is related to the update of 4.4 as I did not update anything else, no plugins and other code/things were changed, no pages/posts changed/added, no server settings changes, just WP upgraded.

Before the update everything was working, afterwards not.

Also in the Apache logs this "redirection" shows up as a 301 (permanent move).
Note: To be sure that it is not caused by external influences/server I cleared .htaccess files to the bare minimum, made no difference.

Also it ONLY happens to SOME of pages, 95% of all pages are working correctly.

The pages in question cannot be accessed as they require usernames/passwords. I am happy to find the bug myself, but I need pointers were to start looking and how this could be caused, what changes in 4.4 might lead to this issue.

For example:

​https://MyDomain.com/lesson/module-0-introduction-module/

gets redirected to

​https://MyDomain.com/lesson/module-0-introduction-module-free/

The content of the two posts are identical, except the top one is a purchased item and part of a very larger course, while the bottom one is free (you just need to register with your email) and is meant to be to show parts of the bigger picture.

IMHO this is not a security issue, as it works on 4.3.1 but not in 4.4.

I am not sure how this could be caused and where.
Happy to provide more info.

[pento]

This sounds like the bug being tracked on #35031. Could you please try the latest patch there to confirm?

[jobst]

Duplicate of #35031.