Downloaded the new patch, go this message when trying to open up a 3rd client. Removed the specified file from Mapleroyals folder and everything worked just fine again but later same message popped up when opening up a 3rd client and the specified file that I had deleted previously had returned. Requires me to close all clients before deleting that file.
The game was attempting to auto-update, so you would need to close all clients and let it patch 1st before opening new clients You may update here if the issue persists