[Mono-list] tracing aspx for HTTP 500 error

Robert Jordan robertj at gmx.net
Sat Jul 22 11:41:25 EDT 2006

Scott Williams wrote:
> Robert Jordan wrote:
>> IIRC, trace.axd never displays exceptions.
>> To see them, use these web.config settings:
>> <configuration>
>> 	<system.web>
>> 		<customErrors mode="Off" />
> Thanks, but that doesn't seem to be it.  Shouldn't a trace.axd page be written 
> for every request when <trace enable="true" pageOutput="false">?  I am guessing 
> the exception is preventing the writing of the page.
> Can anyone confirm that they can see thrown exceptions in trace.axd?

Indeed, unlike MS.NET, Mono doesn't. I filed a bug:


May I ask you why do you need it? The trace is a memory hog, it
disables output caching, it has a limited size and it's not suitable
for logging at all. The trace is intended to be used on-line by
control developers as a debugging aid. It should never be enabled
on productions systems.

If you need true persistent logging you should consider hooking
the HttpApplication.Error event and log the errors to a file
or simply to stderr, which is apache's error log, if you're
using mod_mono. Log4net is also an option.


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