Need help with upgrading

[Wolfy]

well while I was trying to install the update to 1.6.4 from 1.6.2i had an issue because it said that

Fatal error: Call to undefined method datacache::update_threadprefixes() in /home/wolfy/public_html/mybb/install/upgrade.php on line 598

What do I do

[faviouz]

There are hundreds of threads on this, you would have found an answer if you searched the forums.

You most likely downloaded the wrong package (the one that said in red bold text not to use it if you hadn't updated to the original 1.6.4 release yet) or didn't upload all the files. Download the full MyBB package and re-upload all the files, replacing the existing ones.