Unfortunately, disabling plugins and switching the topic failed to solve the problem. I had to abandon this plugin and use another one.
Thanks for the help in any case!
here is a new topic via the control panel (test forum): http://avtovokzal-elets.ru./forums/topic/test-foruma/
A new topic is created using the control panel and added to the forum.
Neither the administrator nor the user can write on the forum.
updated wordpress and bbpress to the latest versions, but unfortunately it did not help.
WP: 4.9.1 bbPress:2.5.14
