We have observed the following issue. For new MS CRM 365 Online organization (taken some days ago) ExecuteRequest fails with error
InvalidOperationException: Metadata contains a reference that cannot be resolved: https://xxxxxxxx.crm4.dynamics.com/XrmServices/2011/Organization.svc?wsdl&sdkversion=90
We use the latest version of MS CRM SDK (version 9.0) downloaded as NuGet package.
It is interesting that if one opens URL https://xxxxxxxx.crm4.dynamics.com/XrmServices/2011/Organization.svc in browser then all seems to be OK: the expected page with Web Service description is showed. So, it seems that the problem is in MS CRM SDK. It doesn't work against new MS CRM 365 Online organization.