Exception deserializing the package “Operation is not valid due to the current state of the object.”. (Microsoft.DataTransformationServices.VsIntegration)
As a professional consultant who has been blogging about SSIS for 12 years and authored and co-authored a dozen books related to Microsoft data technologies, my first response was:
That is a reasonable first response. Fortunately, Andy also had a second response which was more helpful in finding the root cause.