Problem with wpforo

Hi!

Really, very need your help. As usual, at the most inopportune moment, something broke. The forum was configured (and worked) for a very long time. Since then, i only updated versions of plugins and WordPress. Today I needed to use forum and found that it was neither possible to create a new topic or to answer in the old one. Forum swears – “empty message”. As already written – nothing changed in the site and plugins. But I checked all the forum settings, cleaned his caches, recreated topics, etc. – nothing helps. What could be the problem?
WordPress Version 5.4.1
wpforo version 1.7.4

The page I need help with: [log in to see the link]