When you test your ARM template using PowerShell or other techniques before the deployment, you can receive an error: “The template deployment ‘xxxx-xxx-xxx’ is not valid according to the validation procedure. The tracking id is ‘xxxx-xxxx-xxxx’. See inner errors for details.”, and then you may ask yourself – “how to get that inner errors for details?”.
The following PS one-liner can rescue you:
(Get-AzLog -CorrelationId trackingIDhere).Properties.Content.Values
If you don’t have Az module installed, you may use Azure RM module and cmdlet Get-AzureRMLog with the same parameters as for Get-AzLog.
UseIT | Roman Levchenko 
I’ve been stuck on this most of the afternoon, no amount of Googling had helped until I stumbled on this article. I don’t usually comment on posts, but this has helped me find the error in my way.. which in this case was due tot he quota of VM’s being reached so I wasn’t able to deploy more via ARM templates. Thanks a lot for your help!!
You are always welcome! Thanks for the positive feedback.