Solved libraries/kunena/src/Layout/KunenaLayout.php on line 225

I have a new installation of Kunena Version 6.3.7 and i have added template NTS Kbee to it. the Joomla 5 template is called Sombra and is Bootstrap 5 and Helix 2.1
I have migrated from an identical version of Kunena and same template (not Helix though)

I have a couple of issues.
1. When SEF Urls's are on i get 404 errors on every category, when they are off it works but i have the following error where the Kunena menu should be

Debug is on:
2.Rendering Error in layout Widget/Menu: Cannot access protected property Joomla\CMS\Menu\MenuItem::$params in /home/xxxxxxxxxxx/public_html/xxxxxxxxx/libraries/kunena/src/Layout/KunenaBase.php on line 200
Layout was rendered in /home/xxxxxxx/public_html/xxxxxxxxx/libraries/kunena/src/Layout/KunenaLayout.php on line 225

Can anyone suggest how to get this fixed please?

Eliminate template problems. Test with Cassiopeia and Aurelia, with Cassiopeia and KBee and with Sombra and Aurelia.

Thanks yes i should have said , i have tried both default templates and i get exactly the same error, it just looks a bit different !

Then I suppose  it is just an issue with your menu

Wow yes it was, i have to say I wasn't expecting that result, but I trashed (and removed from trash) a Main Menu item for the forum, recreated it again and that has removed the error and replaced it with a nice shiny Menu!

That is the good news

Now I can get to the forum content I am getting a 404 when I click on any of the categories/topics. I have tried switching templates too.

with Debug on I get (in Cassiopeia & Sombra) I get - 404 View not found [name, type, prefix]: category, html, site

Is there a simple fix for this too please?!!
 

SEF enabled and htaccess.txt renamed to .htaccess