In a specific constituent's record, if you navigate to work with gifts from their giving history and then click on Export in the gifts window that opens up this error occurs. The error occurs for all users on all workstations regardless of browser used but is only occurring on the one constituent record.
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
Open the specific constituent record in the NXT web view
On the Giving history panel click on Work with gifts at the bottom of the panel