bbPress.org

WAMP or server installation ?

ok, suggest

You deactivate, delete and re-install bbpress

If that doesn’t work

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.

If those don’t then either maybe corrupt wordpress/server issue.