With Windows Azure Automation Account, you can create some run books for running PowerShell scripts. 
For this, we will need to use PowerShell command lets presents in some modules.
Each module have a version, and sometimes for using new features, we have to update them.
I've been facing to some breaking changes after a version upgrade, and thought I could downgrade the version directly from the Windows Azure Portal. And curiously we cannot.
But there is a small trick, let’s see how to downgrade a module version. 

Actually, when you are using Windows Azure AppendBlob and Windows Azure Data Factory, you are probably facing this issue: 

Error in Activity: Unknown error in module: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.TypeLoadException: Could not load type 'Microsoft.WindowsAzure.Storage.Blob.CloudAppendBlob' from assembly 'Microsoft.WindowsAzure.Storage, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

Let's see what we can do about this.