I would suggest upgrading 1.02 -> 1.1 and then install v2.1.1 of the bbPress plugin and upgrade again checking everything as you go.
Once your old install is fully upgraded go to /wp-admin/export.php and export the Forum/Topics/Replies then /wp-admin/import.php and install the WordPress importer and import that into your other database.
But the forum is on a different database than my wordpress. So I can´t upgrade 1.02 to 2.1.
I´ve already installed BBpress 2.1 on the other database, on my website. But its completely empty. I need to import the data and users from the other forum.
Wait wait wait… I just discovered the Converter!!
That seems to be exactly what I have been asking for! What do I put in the “table prefix”?
I entered bb_ in the table prefix. And I think all the input fields were correct. But it didnt find any data.
It said, no users to convert, no tags to convert etc etc.
It did not convert anything. It seems like it just hit a wall. Whats wrong?