I established a forum on a site in existing Data Base, in the forum catalog of the root folder, but the forum isn't started.

Prompt please in what there can be a reason that it is possible to check.

http://psy-diary.com/forum 

it is good to describe it in an documentation

Not sure what you did, ir maybe I misunderstand, but YAF works fine in a sub folder.

possibly it is feature of my hosting, but works and thank God 🙂

@lifeact any Reason why you installed such an old version (1.95 rc 1) an not the current release (1.96.1)

i instaled forum from Microsoft Web App Gallery and thear thise version. Thanks, how manual update forum? What files i need to replace?

http://forum.yetanotherforum.net/yaf_postst15486_error-while-try-editing-Host-Settings.aspx 

Thanks, how manual update forum? What files i need to replace?

There is a readme.html included that explains how to upgrade, you can also view it only in the wiki

https://yafnet.codeplex.com/wikipage?title=Upgrade&referringTitle=Documentation