How to tell if Application_Error is caused by HTTP error 404?

[Edward]

I have a need to detect if an error is caused by HTTP error 404 in
Application_Error (in global.asax). I read MSDN docs but did not get an
answer.

Is there a reliable workaround to detect this status?

[Bresco]

"Edward" <ne***********@msn.comwrote in message
news:uO**************@TK2MSFTNGP02.phx.gbl...

>I have a need to detect if an error is caused by HTTP error 404 in
Application_Error (in global.asax). I read MSDN docs but did not get an
answer.

Is there a reliable workaround to detect this status?

404 Not Found is caught by IIS, not your webapplication. Your webapplication
will never get this error. What you could do is configure IIS to redirect to
a certain error page which your application could use to detect the 404.

[Edward]

Bresco wrote:

"Edward" <ne***********@msn.comwrote in message
news:uO**************@TK2MSFTNGP02.phx.gbl...

>I have a need to detect if an error is caused by HTTP error 404 in
Application_Error (in global.asax). I read MSDN docs but did not get an
answer.

Is there a reliable workaround to detect this status?

404 Not Found is caught by IIS, not your webapplication. Your webapplication
will never get this error. What you could do is configure IIS to redirect to
a certain error page which your application could use to detect the 404.

I can trap 404 error by <customErrorsin web.config. I have tested this
in IIS and it's working.

I find a way to check 404 in Application_Error:

File.Exists(this.Request.PhysicalPath);

But I am not sure if it is reliable.