Printing apparatus, control method, and storage medium

A control method for a printing apparatus having a scanner, a printer configured to start to print images of the originals read by the scanner before the reading of the plurality of originals is completed, a storage, a controller configured to select, from a plurality of printing paper holding units of the printing apparatus, a printing paper holding unit storing printing paper sheets on which the images are to be formed, and a display, the control method comprising:

• reading, via the scanner, a plurality of originals;
• keeping track, via the storage, of the numbers of printing paper sheets stored in a plurality of printing paper holding units;
• and
• displaying, via the display, an error message in a case where the number of the printing paper sheets held in the selected printing paper holding unit is less than a number of the printing paper sheets necessary to complete the printing of the images of the plurality of read originals.