Question

I have the following entry in the web.config:

<customErrors mode="RemoteOnly" defaultRedirect="Error.aspx" />

Is there a way in Error.aspx.cs to obtain the error details so I can save to a file?

Answer 1

You can use Server.GetLastError() to get the last Exception object that was raised:

Exception exception = Server.GetLastError();

Alternatively you may want to look at handling this in the global.asax file in the Application_Error method rather than your custom error page.
There a few different methods described in this Microsoft support article for custom error handling and reporting