bbPress.org

Yes, it’s an issue with bbPress. It’s an issue with WordPress too. It’s an issue that means you need more memory. The memory limit (see the WP Codex for more on WP_MEMORY_LIMIT) means you need to increase your blog’s PHP memory limit. Why they call it limit and not something that implies ‘adding’ I don’t know.

Which usually means your webhost hasn’t allocated enough to run WP/BB. Which means it’s actually an issue with your webhost that MAY be work-aroundable with manual tweaking.

While you’re welcome to try BB_MEMORY_LIMIT (which is the logical name for it), I don’t think it exists.

If you actually read the links I gave you, you’d know that PerishablePress (a fantastic resource) mentions you may be able to increase memory limits by editing wp-config.php like so:

<?php

@ini_set("memory_limit","16M");

Try that on bb-config.php and see how it works.

You’re probably going to need to dig into your php settings to see how much memory you’ve got right now, and how much you have to play with. You’ll need to savvy up on your error logs too, to see where it’s barfing.