A user of TFS 2010 recently reported a problem when configuring it after the installed had laid down the bits. Seems they had installed SQL 2008 to a instance named “TFS_BETA”. They then ran the configuration wizard of TFS 2010 and selected the custom configuration. Almost immediately they were presented with this error:
Team Foundation Server Configuration
TF255186: The following class could not be found: MSReportServer_Instance. The Windows Management Instrumentation (WMI) namespace is: \\DEV-SER-11\root\Microsoft\SqlServer\ReportServer\TFS_BETA\v10. The instance of SQL Server Reporting Services is: TFS_BETA.
The issue here is that underscore is not a valid character for FQDN’s and as such cause issues with Web applications that use session cookies (such as Reporting Services). We have seen this with VSTSWA as well, and even documented it:
The fix in this case with TFS 2010 and SSRS was to create an instance without an underscore in the name.