Image forming system, control method, and control program

A method of controlling an image forming system including

• a sheet conveyor including a conveyance path and which conveys a sheet along the conveyance path,
• an image former provided on the conveyance path and which forms an image on the sheet, and
• a sheet discharger provided on a downstream side in a sheet conveyance direction of the image former and which discharges the sheet to an outside,
• the method comprising:
• (a) determining, in a case where abnormality occurs in sheet conveyance on the conveyance path, after stop processing of stopping sheets other than a jammed sheet at predetermined stop points according to conveyance positions at the occurrence of the abnormality, the jammed sheet being a cause of the abnormality in the conveyance path, is executed, whether a first residual sheet that needs to be moved before the jammed sheet is removed is included in a plurality of the sheets stopped at the stop points;
• and
• (b) executing first automatic purge processing of conveying and discharging the first residual sheet to the sheet discharger before the jammed sheet is removed, and second automatic purge processing of discharging a second residual sheet different from the first residual sheet, of the sheets stopped at the stop points, to the sheet discharger, after the jammed sheet is removed, according to a determination result of (a).