Try using Server.GetLastError().InnerException.Message;

It shouldn't throw an exception from the code you ahve but it sounds like the Exception doesn't like .ToString(). It's the message you want though...

+++ Rick --

>>So what happens if an error occurs?
>
>The default "Error in the application. Description: An unhandled exception occurred..." page.
>
>>The most likely scenario is that you have an error in the error handler in which case you get a standard ASP.Net error behavior that's virtually undistinguishable from the original error.
>
>Sounds like VFP - you can't handle an error when you're in an error condition, huh? <g>
>
>As far as I know, there isn't an error in the Application_Error code, the exception being reported is the exception that I'm explicitly throwing, not an error in Application_Error.
>
>> THe easiest thing to do is set a break poin t the first line and see if it gets there.
>
>No Page_Error, but setting a breakpoint is behaving strangely.
>
>If I set a breakpoint on the first line of code below in my Application_Error...
>
>

>string ErrorDescription = Server.GetLastError().ToString();
>string RedirectString = "Error.axpx?ErrorDescription=" + ErrorDescription;
>Response.Redirect(RedirectString);
>Server.ClearError();
>

>
>The debugger stops at that first line of code, and taking a single step at that point throws me into the default "unhandled exception page". The remaining three lines of code do not appear to execute.
>
>If OTOH, I change the code like this, clearing the error before doing the Response.Redirect():
>
>

>string ErrorDescription = Server.GetLastError().ToString();
>string RedirectString = "Error.axpx?ErrorDescription=" + ErrorDescription;
>Server.ClearError();
>Response.Redirect(RedirectString);
>

>
>The debugger again stops at the first line of code, and taking a single step beyond that is leaving me at the page in which the error occurred, but it's now blank. Again, it would appear that the remaining three lines of code aren't running, so I don't know why the behavior would change.
>
>I have no idea at this point what's going on...