Setup:
I installed Microsoft Visual Studio Team System, with a single server Team Foundation Server (TFS) configuration. The configuration are using domain users as setup, service and reportings useres.
Problem:
During installation of Team Foundation Server, the 26105 error occured, after the installation Wizzard validated system requirements and the installation process started.
Solution:
After investigating the installation log, it seams like the problem is related to creating the TFS SharePoint site. Even though I followed the installation guidance it seams the setup user doesn't have the enough privileges to create the TFS site. The setup user was created as a domain user with local administration privileges. To correct the problem I added the TFSSETUP user to the STS_WPG group on the local machine.