You receive the generic error message:
There has been a serious error loading the forum. No futher information is available. Please contact the administrator if this message persists.
First step is to figure out what caused the error. To do that, open web.config file (in your application root directory), and modify this line:
<esc><customErrors defaultRedirect="error.aspx" mode="RemoteOnly"/></esc>
change it to:
<esc><customErrors defaultRedirect="error.aspx" mode="Off"/></esc>
then upload it, run your site and see what error you are getting.
If you do not have the web.config file in your application root directory, you need to read the installation instructions again (INSTALL.TXT) as they explain how to setup your base forum configuration.
If you still don't know how to solve the problem, please
go to the support forum,
make a topic and post the entire exception error message so that someone in the YAF support community can assist.