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.


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.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


Learn about the terminology that Microsoft uses to describe software updates.

Need more help?

Expand your skills
Explore Training
Get new features first
Join Microsoft Insiders

Was this information helpful?

What affected your experience?

Thank you for your feedback!