Line numbers missing from exception stack trace when ASP.NET impersonation enabled

An ASP.NET 2.0 web application has been compiled with PDB symbols, deployed to a server running IIS 6.

In the web.config, user impersonation is enabled:

  <identity impersonate="true" />

When an Exception is thrown, the stack trace is missing line numbers, making it very difficult to determine exactly where the exception is emanating from. eg.

System.NullReferenceException: Object reference not set to an in开发者_JS百科stance of an object. at MyApp.ReportingServices.WebForm.DA.AmoRepository.GetDimensions(String perspective)

The login being used to access the website has no special rights or group membership on the server.

I managed to get a detailed stack dump for the exception by assigning the 'Debug Programs' user right to the particular login.

Once the exception was diagnosed I removed that user from that assignment.