[nekita]

Narrowing down on the problem, I’m now able to log in even with the integration code added (by using the exact same setting for WordPress address and Blog address as used in General Settings), however the account is extremely limited in use.

It’s basically the same issue described by user doyle640 here (https://bbpress.org/forums/topic/wordpress-and-bbpress-integration-101/page/3), the Admin screen is unaccessable (blank page) as well as the Profile edit options, even the form to add a new topic is completely missing.

This is true for the Admin account as well as any user account.

Once the line “require_once(‘../wp-blog-header.php’);” is deleted from bb-config.php, everything is accessable as usual.

The login synchronization now works both ways as it should though.