iExpense - You have encountered an unexpected error. When Trying to View Previously Submitted ER

Hello, I have a user that's trying to view his previously submitted expense reports in R12.1.3. When he navigates to the Expense Reports tab and then tries to click on an ER from April of 2016, he gets this erorr page with the generic message of "You have encountered an unexpected error. Please contact the System Administrator for assistance." This doesn't happen when he chooses other expense reports that are back from 2016 or older  just seems to be this one ER. I set myself up as a delegate and I get the same error when trying to view just