NServiceBus - messages going to error queue but no exception logged?

I've got some messages that are intermittently failing in production and ending up in the error queue. Each time I run ReturnToSourceQueue, a proportion succeed, and a proportion fail again (so if I keep running ReturnToSourceQueue eventually all of them empty from the error queue).

What I can't figure out is why I'm not seeing any exceptions in the logs? For the messages that succeed, I see a "Received message..." entry in the log4net logs, and it appears in the audit queue. However, for t开发者_Python百科he messages that fail, they go to the error queue, but there's no log entry.

The process that's receiving these messages is an ASP.NET application if that makes any difference.

Does anyone have any pointers?

Thanks

Do you have a try-catch inside your message handler? This may be masking the error.