[wp-trac] [WordPress Trac] #33702: Editor strips line breaks

[WordPress Trac]

#33702: Editor strips line breaks
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 Reporter:  Cyril Washbrook  |      Owner:
     Type:  defect (bug)     |     Status:  new
 Priority:  normal           |  Milestone:  Awaiting Review
Component:  Editor           |    Version:  4.3
 Severity:  normal           |   Keywords:
  Focuses:                   |
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 Since upgrading from WP 4.2.4 to WP 4.3, the editor has been stripping
 line breaks from all posts and pages. Clearly, this cannot be affecting
 everyone, but I suggest, for the reasons that follow, that there is at
 least some reason to believe that the error stems from some flaw in WP 4.3
 itself.

 The problem unfolds as follows:
 (1) I start with WP 4.2.4.
 (2) I update WP 4.3 (either manually or automatically).
 (3) There is initially no change to pages/posts immediately after the
 update.
 (4) When I open a post or page and edit it, the line breaks vanish.
 (5) If I try to add line breaks, they are stripped out again when I save
 or publish the post (or when I switch from code view to WYSIWYG view).

 I have done all of the following:

 (1) disabled all plugins;
 (2) switched to several Wordpress default themes;
 (3) manually downgraded to 4.2.4 and upgraded (both manually by FTP and
 automatically) again to 4.3;
 (4) accessed the site through Chrome, Firefox and IE.

 Further information:

 (1) Manual downgrades and upgrades have been done by deleting the `/wp-
 admin` and `/wp-includes` directories and uploading freshly downloaded
 files, and uploading the "loose" files to the top-level directory.
 (2) At no stage have I edited, added to or removed any core files (not
 that this should make a difference in light of the various steps I have
 taken).

 The results:

 (1) The problem only occurs in 4.3.
 (2) Downgrading to 4.2.4 always resolves the problem.
 (3) The problem persists when all plugins are disabled and one of the
 default themes is activated.
 (4) The problem occurs across all browsers.

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Ticket URL: <https://core.trac.wordpress.org/ticket/33702>
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