[wp-trac] [WordPress Trac] #55734: Only the 'Plain' setting works / incompatible with some plugins

[WordPress Trac]

#55734: Only the 'Plain' setting works / incompatible with some plugins
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 Reporter:  redglyph      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  General       |    Version:  5.9.3
 Severity:  major         |   Keywords:
  Focuses:                |
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 The installation by default seems to work correctly. If I change the
 Settings / Permalinks / Common Settings to another option than 'Plain',

 - I cannot access the existing posts anymore, they lead to a 404
 - If I try to create a new post, after clicking and confirming 'Publish',
 I get a "Publishing failed. The response is not a valid JSON response." in
 a red banner at the top
 - I see that the URL, when I hover a post title with my mouse, changes
 accordingly to the new setting (so at least that part works)

 I was expecting
 - the existing page URLs to be adapted to the new setting
 - being able to create new posts after changing to the new setting

 Moreover, important plugins like wpForo don't work with the default
 'Plain' setting.

 WordPress: Version 5.9.3
 Apache version: 2.4.53-1
 PHP Version: 8.1.4
 MySQL version: MariaDB 10.7.3

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Ticket URL: <https://core.trac.wordpress.org/ticket/55734>
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