Debugging Windows Azure DevFabric HTTP 500 Errors 

While developing with Windows Azure SDK and local Azure development fabric, when things go wrong, they go really wrong.

It could something as obscure as leaving an empty element somewhere in Web.config or a certificate issue.

The problem is, that before Visual Studio attaches a debugger into a IIS worker process, a lot of things can go wrong. What you get, it this:

There's no Event Log entry, nothing in a typical dev fabric temp folder (always, check 'C:\Users\\AppData\Local\Temp\Visual Studio Web Debugger.log' first), nada.

Poking deeper, what you need to do is allow IIS to respond properly. By default IIS only displays complete error details for local addresses. So, to get a detailed report you need to use a local address.

You can get a local address by fiddling with the site binding with IIS Manager and changing what Azure SDK does, so:

  • First, start IIS Management Console.
  • Then right click on your deployment(*).* and select Edit Bindings.
  • Select All Unassigned

If you hit your web / service role using the new local address (could be something like, you are most likely getting the full disclosure, like this:

In this case, a service was dispatched into dev fabric, which had an empty element somewhere in Web.config. The web role was failing before Visual Studio could attach a debugger, and only HTTP 500 was returned through normal means of communication.

Categories:  .NET 4.0 - WCF | Windows Azure
Wednesday, 10 April 2013 15:04:49 (Central Europe Standard Time, UTC+01:00)  #    Comments


 The Case of Guest OS Versioning in Windows Azure 

There's a notion of Windows Guest OS versions in Windows Azure. Guest OS versions can actually be (in Q1 2012) either a stripped down version of Windows Server 2008 or a similiar version of Windows Server 2008 R2.

You can upgrade your guest OS in Windows Azure Management Portal:

Not that it makes much difference, especially while developing .NET solutions, but I like to be on the newest OS version all the time.

The problem is that the defaults are stale. In 1.6 version of the Windows Azure SDK, the default templates all specify the following:


The osFamily attribute defines OS version, with 1 being Windows Server 2008 and 2 being Windows Server 2008 R2. If you omit the osFamily attribute, the default is 1 too! Actually this attribute should probably move to the Role element, since it defines the version of the role's guest OS.



It doesn't make sense to have it normalized over all roles. Also, this schema makes it impossible to leave it out in VM role instances, where it gets ignored.

The osVersion attribute defines the version which should be deployed for your guest OS. The format is * or WA-GUEST-OS-M.m_YYYYMM-nn. You should never use the latter one. Asterisk, normally, means 'please upgrade all my instances automatically'. Asterisk is your friend.

If you want/need Windows Server 2008 R2, change it in your service configuration XML.

What this means is, that even if you publish and upgrade your guest OS version in the Azure Management Portal, you will get reverted the next time you update your app from within Visual Studio.

Categories:  Windows Azure
Sunday, 31 March 2013 21:40:01 (Central Europe Standard Time, UTC+01:00)  #    Comments


 The Case of Lightweight Azure MMC Snap-In Not Installing on Azure SDK 1.6 

There are a couple of Windows Azure management tools, scripts and PowerShell commandlets available, but I find Windows Azure Platform Management Tool (MMC snap-in) one of the easiest to install and use for different Windows Azure subscriptions.

The problem is the tool has not been updated for almost a year and is this failing when you try to install it on the latest Windows Azure SDK (currently v1.6).

Here's the solution.

Categories:  Windows Azure
Tuesday, 26 March 2013 11:36:53 (Central Europe Standard Time, UTC+01:00)  #    Comments


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