3814421 - Error: "The itinerary you're requesting cannot be booked in Concur Travel"

In an approved request that has Book Travel button, clicking on this button generates an error message:

"The itinerary that you're requesting cannot be booked in Concur Travel:
We encountered an error while trying to process your request.
Please review your request and contact your Administrator."

I submitted a request that was fully approved and is now in the pending booking stage. However, when I attempt to click on the "Book Travel" button, I encounter an error message. , KBA , CON-EXP-TRS , Trip Segments / Reservations , Problem