Unlike some ASP.NET WebControls, an error can occur within RAD PDF without an ASP.NET exception being raised. There are several locations to look for information about RAD PDF errors and exceptions.

• Windows Event Viewer - The Windows Event Viewer is the most comprehensive place to start troubleshooting. The RAD PDF System Service logs information, warnings, and errors to the Application Log using the Source "RAD PDF". Critical HttpHandler errors are logged to the Application Log as well. (Visibility into a custom HttpHandler can sometimes be difficult; as such, RAD PDF logs important notifications here.) ASP.NET also logs warnings here such as unhandled ASP.NET exceptions which may be useful in troubleshooting your RAD PDF configuration.
• Client Browser - As you likely know, if your web.config file is configured to display descriptive debug information, unhandled ASP.NET exceptions will render information about the exception. If using a browser which supports resource inspection (e.g. Internet Explorer with Internet Explorer Developer Toolbar, Firefox with Firebug), HttpHandler error information will be made available to you. (Without resource inspection, the more detailed error descriptions returned by the RAD PDF HttpHandler are not displayed directly in the browser.)
• Error Catching - RAD PDF's WebControl exposes the RadPdfException class (and its inherited exceptions) which is raised for many RAD PDF specific problems. These exceptions can be handled using try / catch blocks to diagnose WebControl issues related to your RAD PDF configuration in a custom manner.