I have updated to 3.2.0 stable from 3.2.0-beta5-dev (test-passed) and no problem at all.
Just stopped the forum, edit app.yml and uncommented the line #version: test-passed and changed it to version: stable.
Then run the following commands:
git pull
launcher rebuild app
wait to the rebuild process to end and all is ok, now it is running 3.2.0 stable version.
Thanks to all for the received help