This message appears very infrequently for Requestors, but is part of the normal system operation.
Landport regulates the number of reports that Managers can run simultaneously in order to maximize system resources. On some occasions, there is an extremely high demand for reports across the entire Landport base.
Even though Requestors cannot generate reports, if they try to submit a request within 60 seconds of a large report run, the "Report Server is completing another request..." message will appear. The Requestor can press the "Back" arrow on their browser, wait 30 to 60 seconds, and then resubmit the request.
We are always upgrading our system resources, so this should be an infrequent occurrence, but if you have it happening more than one or two times, please submit a Support ticket.