Skip to main content

IIS and ASP.NET 404 error handlers don't play nicely together

While trying to setup both ASP.NET as well as IIS error-handling, I noticed that IIS wasn't dealing with certain 404 errors in which the file extension was wrong.  For example, I could request ThisFileDoesntExist.aspx and that would redirect to NotFound.aspx just fine, but WrongExtension.aspz would kick the user out to the ugly default IIS 404 error page.

So I did a bit of investigation and found this post, which pointed out that, in your web.config, if you have both this (relevant parts highlighted):

<customErrors defaultRedirect="~/Error.aspx" mode="On" redirectMode="ResponseRedirect">
    <error statusCode="404" redirect="~/NotFound.aspx" />
</customErrors>


As well as this:

<httpErrors errorMode="Custom" existingResponse="Replace">
    <remove statusCode="404" subStatusCode="-1" />
    <error statusCode="404" prefixLanguageFilePath="" path="/NotFound.aspx" responseMode="ExecuteURL" />
</httpErrors>


For some reason beyond my knowledge the IIS error handler just doesn't fire, somehow the ASP.NET 404 handling hijacks the process but doesn't get called in the event of unknown file extensions.  However, removing the 404 element from the <customErrors> section lets the IIS error handling deal with every case, and all is well in my website once again.  It makes me wonder why the customErrors section even lets you deal with 404s if it doesn't work as expected?  But that's probably more of a gap in my knowledge than it is an issue with IIS/ASP.NET.  Have more insight into what's going on? Let me know!

Comments

Popular posts from this blog

Using Log4Net to use both event log and a rolling log file

Here's the config section, note that the applicationNameproperty in the EventLogAppender needs to be the same as the event source in the windows event log that you want to log to.  If the event source doesn't exist, that appender won't work.  In this particular project I create that during install using WiX (which is covered in another post)

  <log4netdebug="true">
    <appendername="RollingLogFileAppender"type="log4net.Appender.RollingFileAppender">      <filevalue="log.txt" />      <datePatternvalue="dd-MM-yyyy" />      <appendToFilevalue="true" />      <locationinfovalue="false" />      <rollingStylevalue="Size" />      <maximumFileSizevalue="1MB" />      <maxSizeRollBackupsvalue="10" />      <staticLogFileNamevalue="true" />      <layouttype="log4net.Layout.PatternLayout">        <conv…

Using WiX to create an event source during install of a .NET framework project

Edit: so I guess I wasn't the only one confused with this stuff, as it's been my most popular post by far!  If I've helped you out or saved you some time, please let me know in the comments :)

In order for this to work, you have to add references to WixUtilExtension and WixNetFxExtension to your WiX project.  Once that's done, add this inside a <Component> element:

<Util:EventSourcexmlns:Util="http://schemas.microsoft.com/wix/UtilExtension"Name="EVENTSOURCEGOESHERE"Log="Application"EventMessageFile="[NETFRAMEWORK40FULLINSTALLROOTDIR]EventLogMessages.dll" />
Obviously replace EVENTSOURCEGOESHERE with your event source name.  NETFRAMEWORK40FULLINSTALLROOTDIR is a property set by the WixNetFxExtension which stores the path to the .NET framework v4 directory, but you can replace this with the corresponding property for the directory containing the relevant EventLogMessages.dll file.  So if you're using the .NET framewo…

How to make yourself a Dynamics CRM 2011 Deployment Administrator

Today I needed to deactivate one of our Dynamics organisations, but when I opened the Dynamics Deployment Manager, I received the following error:

"Only the Deployment Administrators are able to use Deployment Manager. You are not a Deployment Administrator."
Bummer. I did a bit of Googling and found this post by Ronald Lemmen (thanks for pointing me in the right direction!).  Since the Dynamics Deployment Manager is obviously checking the MSCRM_CONFIG database for this information I attached a database trace to it and found that it's executing these queries (among many others):

exec sp_executesql N'SELECT  Id, [DefaultOrganizationId], [IsDisabled], [Name]   FROM [SystemUser]   WHERE ((([Name] = @Name0)) ) AND (IsDeleted = 0) ', N'@Name0 nvarchar(41)',@Name0=N'{My windows domain account}'
exec sp_executesql N'SELECT  Id, [Name], [UniqueifierId]   FROM [SecurityRole]   WHERE ((([Name] = @Name0)) ) AND (IsDeleted = 0) ', N'@Name0 nvarchar…