But they are working fine in comments. Also, the preview tab for the description field works also fine, so the html-encoding is probably done during save (or load?) time.

For example:

 
blabla
 

becomes

<pre>blabla</pre>

after saving, and opening for re-edit.

The problem appeared after upgrading to 4.0.6 from 2.4 (step-by-step of course, installing each major version).

I would first like to ask other 4.0 users if this bug exists for them, too.

Environment:
  Redmine version                4.0.6.stable
  Ruby version                   2.5.5-p157 (2019-03-15) [x86_64-linux-gnu]
  Rails version                  5.2.4.1
  Environment                    production
  Database adapter               Mysql2
  Mailer queue                   ActiveJob::QueueAdapters::AsyncAdapter
  Mailer delivery                smtp
SCM:
  Subversion                     1.10.4
  Git                            2.20.1
  Filesystem                     
  Xitolite                       2.20.1
Redmine plugins:
  additionals                    2.0.22-1
  allmyissues                    0.0.1
  issue_hot_buttons              0.4.4
  line_numbers                   1.0.0
  my_projects                    1.4
  periodictask                   4.1.0
  redmine_bootstrap_kit          0.2.5
  redmine_favourite_projects     1.0
  redmine_git_hosting            4.0.1
  redmine_people                 1.4.0
  redmine_reminder               0.2.2
  status_button                  0.1.0