Upgrading Umbraco
Stop IIS Site (this is really important!)
Download the new version of Umbraco, and copy across these
folders to your wwwroot folder.
/bin
/umbraco
/umbraco_client
/install
Question Overwrite Files = YES
Recheck file permissions (see install guide here)
*If you are upgrading Umbraco 3 to 4, you may have old
packages which are not compatible with datalayer (photo crop tool
for example). A short term fix for this issue is to open the
web.config file and remove 'datalayer' from the database
string.