3812461 - Why is the user getting "Error: There was an error saving your expense" when saving an expense entry using the NextGen UI for Concur Expense?

One of our users is receiving the below error when trying to save an expense entry inside an expense report. It is only happening for a specific expense type and we're using the NextGen UI for Concur Expense.

User is getting an error while trying to save an expense entry inside an expense report. It is only happening for a specific expense type. , KBA , CON-CA-ADM , Administration , Problem