It could be a theme or plugin issue
Plugins
Deactivate all but bbpress and see if this fixes. if it does, re-enable one at a time to see which is causing the error.
Themes
If plugins don’t pinpoint the problem, as a test switch to a default theme such as twentyfifteen, and see if this fixes.
Then come back
I led the action of removing / recreating the splugin.
After searching, it turns out that my user profiles have changed and have all become “Participant”.
By logging in as admin, I was able to reassign rights.
Thank you Robin for your help.