CANON MF4140 'LOAD CORRECT PAPER CASSETTE : LTR'
I had same thing happen after a fresh Windows install. It was hard to figure out since it had been working fine until then, but luckily it is simple to fix. Open the Start Menu > Settings > Printers and Faxes folder. Then right-click on the Canon MF4100 Series printer and choose Printing Preferences. In there, change the Paper Size to Letter (instead of A4). You may also have to do this in the Print setup for whatever program you're using to print.
5 hours ago