I often get questions similar to:
“We are trying to do X – but we only see ‘Sorry, an error occurred while processing your request.’ in the browser. What am I missing”
Well – that means an error has occurred..and there are two ways to troubleshoot –
The “quick and dirty” solution is to turn off custom errors. For that modify the customErrors element in web.config. That will give you the ‘yellow screen of death’ with exception text, stack trace etc… (don’t forget to turn that off again).
…or check out this article about tracing.