If this happens to you and you switch the number to zero but it doesn’t work and if you check your logs you will see this:
Uncaught DivisionByZeroError: Division by zero in []/wp-content/plugins/bbpress/includes/admin/classes/class-bbp-converter.php:390
Use phpMyAdmin or your favorite DBM flavor and go into wp_options.
Manually change the row “_bbp_converter_rows” from zero to whatever you initially had. Be sure to update it in the converter pane as well otherwise the original value will not take.
