We have a SQL Server 2008 R2 Report Server running under Basic Authentication mode. This is recently upgrade report server.
When a user tried to access Report Builder, user gets
401 – Unauthorised
error message.
As per Microsoft documentation Configure Basic Authentication on the Report Server, it suggests that Basic Authentication is not supported for ClickOnce application installer, which is used by Report Builder application.
To work around this issue, article suggests to configure Anonymous Access to the Report Builder program files.
This is done by adding following tag in RSReportServer.config under block.
True
Save the config file and restart report server.
This should resolve and allow report builder to be accessed by user.
ujjavalsuthar 