While taking a look at the new Outlook Addin Ribbon Commands I came across these schema validation errors trying to deploy the addin once I added the VersionOverrides element. In particular I was getting this error message:
Failed to deploy the manifest file to the Exchange server. This app can’t be installed. The manifest file doesn’t conform to the schema definition. The element ‘Resources’ in namespace ‘http://schemas.microsoft.com/office/mailappversionoverrides’ has invalid child element ‘Images’ in namespace ‘http://schemas.microsoft.com/office/officeappbasictypes/1.0′. List of possible elements expected: ‘ShortStrings, LongStrings’ in namespace ‘http://schemas.microsoft.com/office/officeappbasictypes/1.0′... The element ‘Resources’ in namespace ‘http://schemas.microsoft.com/office/mailappversionoverrides’ has invalid child element ‘Images’ in namespace ‘http://schemas.microsoft.com/office/officeappbasictypes/1.0′. List of possible elements expected: ‘ShortStrings, LongStrings’ in namespace ‘http://schemas.microsoft.com/office/officeappbasictypes/1.0′.
After a bit of trial and error I discovered that the issue was to do with the order of child elements within the Resources element. It appears that there is a strict order that must be adhered to.
Here’s the code that was causing the error. Notice that I was defining Urls before Images.
I simply swapped this around to define Images first, then Urls and the xml then passed the validation check and I was on my way. Here’s the working code:
Cameron Dwyer 
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