Okay I finally can see your forum It must be closed to guests.
After I registered I can see something.
The whole site looks hosed up Duplicate forums, Menu item text missing etc.
Could be paths are not all correct, corrupted files for what ever reasons, not uploaded in ascii or upgrade was done incorrectly
You need to first verify the correct paths to see if they need to be changed.
So after all that you have 3 options I see.
1.Install a fresh net new install to test if it is your new server and correct any paths. Then you can upgrade.
2.Redo the upgrade completely and follow the docs completely.
3.Open a support ticket.
I can't help much more with out full access. I don't know what else to tell you.
