Came across an error last week whilst running the Office 365 Hybrid wizard with an Exchange 2010 server. After entering the 365 and on-premise credentials, the wizard would fail with the error :-
Could not find property ‘InitialDomain’ in object Deserialized.Microsoft.Exchange.Data.Dictionary.SystemConfiguration.AcceptedDomain. Parameter name: InitialDomain
Turns out that the version of the Hybrid wizard that was available at the time had a fault with it. For some reason it was looking for a value that is not present in Exchange 2010. It only exists in 2013 onwards.
In the end I had to install an Old version of the Hybrid Wizard supplied by Microsoft. I have attached the version below.