Old phpBB forum moved into bbPress on WordPress

An old phpBB board moved into bbPress on WordPress. I carried across the whole category structure, the posts, attachments, users and groups, so none of the forum's history got left behind.

The objective

The client wanted their forum inside WordPress instead of sitting next to it as separate software. The board ran on a very old phpBB version, old enough that most of the ready-made converters won't touch it.

The list of things that had to survive the move was long. The whole section and category hierarchy, exactly as it stood. Every post and page. Custom fields, comments, images, file attachments, and all the users with their group memberships.

phpBB and bbPress don't model any of that the same way, so before I wrote a line of migration code I had to work out what maps to what.

What I did

I mapped the phpBB structure onto its bbPress and WordPress equivalents, and made a call everywhere the two didn't line up.

I moved the content over in stages and checked the counts after each one, rather than running the whole thing and hoping the totals matched at the end.

Attachments and images went into the WordPress media library with their post associations kept intact.

I migrated the users and their groups too, so existing accounts still worked once they landed.

The result

The community came out running on bbPress inside WordPress with its history intact, and the client had one system to look after instead of two.