Solved Forum lost categories after upgrade to J4

Yes thanks. Nothing else seems to be working at all.

We have the exact same issue here after upgrading.
So this is not an isolated issue.

www.kunena.org/docs/en/basics/upgrade/upgrade-k6-0
if you read this explanation = Especially point 2 is important
Uninstall Kunena through the Joomla extension manager
are you sure you did that.

Yes we did try to uninstall using the J3 extension manager prior to migrating, but it didn't uninstall the extension but resulted in an error (sorry, I didn't save the error message). So I manually uninstalled the extension (removing  all the plugins components etc, then making sure all the folders were removed, then removing it from the _extensions table). And still ran into this problem.

And, due to the complexity and size of this site, we really didn't want to spend time re-migrating the previous J3 to J4 not knowing if it would work again.

HOWEVER ... I was able to get it working by manually migrating the data into a clean install.

1. I had a SQL back-up of each of the Kunena tables from our J3 site.
2. I completely removed Kunena from J4 - using the tools area to remove it - so everything was wiped out
3. Re-install latest 6.x version of Kunena in J4
5. Manually import via SQL all the data from the old tables*
6. Manually set all the Configuration settings via the Kunena configuration screen
7. Re-created all the Kunena menus on the J4 site

Once that was done everything appears to be working fine.

*NOTE: If you try to do this, there are a bunch of fields in two tables that have been renamed in Kunena 6.x:

categories:

parent_id >> parentid
pub_access >> pubAccess
pub_recurse >> pubRecurse
admin_access >> adminAccess
admin_recurse >> adminRecurse
allow_anonymous >> allowAnonymous
post_anonymous >> postAnonymous
allow_polls >> allowPolls
topic_ordering >> topicOrdering
allow_ratings >> allowRatings

ranks:

rank_id >> rankId
rank_title >> rankTitle
rank_min >> rankMin
rank_special >> rankSpecial
rank_image >> rankImage

If you don't rename the fields in your sql imports, then you'll just get errors.
 

I followed your explanation.
With the exception that after kunena version 6 I was uninstalled.
I first imported the old kunena V5 data .sql.
And I also saw in Maintenance: Global Check-in that category table of kunena had to be checked in there.
but further your adjustments in categories and ranks
done and yes I must say then it does indeed work.
But then it is also to be hoped that one will also be there somewhere
the old kunena v5 media files is called saved so
one can still use it.

Can we please try to solve the problems one by one? It is simply too exhausting when various errors are to be fixed in a single topic.
The fact that you can't open themes is probably because no categories are published. I've noticed that categories that are not published still show as published in the backend. Publish some categories and then try to create a topic.

By the way: The database collation for Joomla 4.x and Kunena 6.x should be utf8mb4_unicode_ci or utf8mb4_general_ci.