Symptoms
In a Microsoft Exchange Server environment, when you perform an eDiscovery search and then export the results through the eDiscovery PST Export Tool, the export never finishes, and you receive the following error message:
Export failed with error: Export failed with error type: 'Unknown'. Details: Value cannot be null.Parameter name: key.
Cause
This issue occurs if the Item property has a null value when results are exported.
Cumulative update information
For Exchange Server 2013
To resolve this issue, install Cumulative Update 15 for Exchange Server 2013 or a later cumulative update for Exchange Server 2013.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.
