Elmah.ErrorMailModule.ReportError error throwing a FormatException, which recycles the w3wp process

Question

Recently, I've noticed that a web application in IIS is restarting randomly, sometimes every 20 minutes. I've checked the Event Log, and found various errors of:

• Level: Error
• Source: .Net Runtime
• EventID: 1026

Below is the exception details:

Application: w3wp.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.FormatException
Stack:
   at System.Text.StringBuilder.AppendFormat(System.IFormatProvider, System.String, System.Object[])
   at System.String.Format(System.IFormatProvider, System.String, System.Object[])
   at Elmah.ErrorMailModule.ReportError(Elmah.Error)
   at Elmah.ErrorMailModule.ReportError(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

I am using the latest stable version of Elmah (1.2.2). Below is the <elmah> configuration node in web.config

<elmah>
    <errorLog type="Elmah.XmlFileErrorLog, Elmah" logPath="~/App_Data/errors/" />
    <security allowRemoteAccess="1" />
    <errorMail from="[email protected]" to="errors@casasoft-dev" subject="{Error_Encountered} [Visit Gozo]" 
               async="true" smtpPort="25" smtpServer="mail.casasoft.com.mt" userName="errors@casasoft-automailer" password="RvjyBiyvePVVpcLBNgJ6" />

</elmah>

I am setting it to send such emails in async-mode (async="true"). If these are spawned on a background thread, and an error occurs on a backgroung thread, as far as I know the process is terminated.

Any ideas what can be done?

I am using IIS7, and ASP.Net MVC 4.

Answer 1

I've raised an issue on Google Code related to ELMAH, and I got a reply from one of the developers.

Basically, it seems that the email subject is internally in Elmah using string.Format() to format it with the error message {0}, and error type {1}. In my case, the subject I specified in the settings was:

{Error Encountered} Website_Name

The {} where triggering a FormatException, hence the issue. This was easily resolved by replacing these with round-brackets, as I had no need for the curly brackets. One could escape them by doing {{ and }} , but in my case it was unnecessary.